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  • 1.
    Wiklund, Viktor
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Boliden Mineral AB.
    On Cone Penetration Tests in Tailings: The need for a calibration chamber2024Licentiate thesis, comprehensive summary (Other academic)
  • 2.
    Ziagharib, Alaleh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical properties of excavated sulfur rich soil stabilized with cement - A laboratory and field experiment2023Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sulfide soils are silty soils, often found in saturated conditions, under the groundwater level. Characteristics of these soils, including particle size distribution and consistency limits along with chemical composition and environmental properties, cause excavation to be necessary for construction purposes. The excavated sulfide soil usually is transported and deposited in landfills. These soils are either deposited in saturated conditions or chemical buffers are added to the soil to prevent acidification. Special conditions of these landfills complicate the disposal procedure and the landfill maintenance which makes those financially expensive. Reusing sulfide soil in construction is a solution to reduce the expenses related to the management of sulfide soils. Since the mechanical properties of these soils are not suitable for construction purposes, the first step is to improve soil characteristics to the level that fulfills the needs of construction applications. One solution to improve the mechanical properties of the soil is adding a binder to the soil.

    The main focus of the research was to improve the mechanical properties of soil. The research activities were divided into two parts. The first part was conducted in a laboratory environment to develop mixtures, while the second focused on transferring the results to field conditions. The laboratory tests included mixing soil and binder i.e., cement was added to the soil at different percentages to evaluate the soil improvement. An unconfined compressive strength (UCS) test was conducted on the stabilized sample to evaluate the efficiency of the stabilization. The resultsof UCS for the stabilized samples were compared. Since the soil contains a high amount of water, the traditional sample preparation was not suitable. Therefore, an alternative method was developed and evaluated. Moreover, the effect of curing time on the strength and consistency limit of stabilized samples was evaluated. At last, the effect of different variables, including porosity, binder content and initial water content, on the UCS of soil was investigated to identify potential correlation between UCS and different soil variables.

    The results of the tests showed that adding a binder, regardless of the type of sulfide soil, positively affects the UCS of prepared samples and increasing the curing time increased the UCS of the samples. At higher cement content, the effect of curing time was more significant. Also, it was shown that at higher water content, the effect of binder is lower in comparison with the same soil at lower water content. By lowering the water content, the strength of stabilized soil reaches a maximum and drying further the soil, below the optimum water content, led to strength reduction. A correlation between UCS of sample and porosity/binder ratio was employed to predict the strength behavior of stabilized soil based on variables such as porosity, initial water content and binder dosage.

    In order to evaluate if laboratory results can be applied to geotechnical applications, the second part of this research included a field mixing experiment for a large-scale mixture of soil and cement. The effect of the mixing procedure with common equipment on the homogeneity of industrial-size mixture was investigated. A sampling strategy for collecting representative samples of mixture was selected and assessed. the number of mixing steps and the effect of binder dosage on the uniformity of samples were studied. Results of UCS of samples prepared from field and laboratory mixture were compared and evaluated. A field evaluation was conducted to determine the quality of the mixture and how many mixing steps are required to reduce variability between samples. Two different percentages of binder were added to the 5 Tons of soil. The UCS test samples were prepared from the soil-cement mixture in the same way as they were prepared in the laboratory and cured for a specific time. The UCS test was conducted on cured samples. The test results were compared to evaluate the mixture homogeneity in the field.

    The results showed that homogeneous mixtures can be obtained in the field with the available equipment. Assessing the sampling strategy showed that increasing the sampling sections from 5 to 12 and preparing single UCS sample from the collected soil provides representative samples from the soil mixture pile. Additionally, it was shown that by increasing mixing steps from 2 to 3, it was possible to eliminate samples with notable lower strength than average UCS. A greater number of mixing steps improves homogeneity while reducing the average UCS. It was found that mixing soil and binder in the laboratory improves strength better than mixing them in the field. When applying laboratory results to field design, this point must be taken into account.

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  • 3.
    Bergliv, Elin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Large-scale testing of granular material2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main problem to investigate in this study is if larger grained materials, up to 200 mm nominal size, could be used as an embankment material for high-speed railways. High-speed railways have very strict settlement requirements, allowing only very small settlements to ensure safety.

    To be able to test large grained materials, large devices and unique equipment is needed, something that makes testing and laboratory investigations rarer with increasing grain size. The studies that have been done focus on materials up to about 200 mm nominal size. The literature review finds that there is unclear common conception of how grain size influences the shear strength and deformation properties of a soil material. The most common finding is that increasing grain size results in lower shear strength and increased deformations. Some studies found the opposite and some found no influence of grain size on shear strength. One observation is that the shear strength tends to be unaffected by grain size if the grain strength is equal for all grain sizes. Otherwise the general impression is that larger grains tend to have higher occurrence of fractures and cracks, lowering the grain strength.

    The study presented herein is performed with a newly developed large-scale simple direct shear device. This device allows testing of grains up to 200 mm grain size. The design includes a free-standing load frame, where the sample is placed in a steel-wire lined rubber membrane on a swing. There are two actuators, one applies vertical force on the sample, while the other applies the shearing motion of the swing. The design is new and allows large forces in both vertical and horizontal direction, without pre-stressing the device.

    A total of six series are performed on materials with varying grain size, gradation, and grain shape. The findings of the laboratory study includes higher shear strength of well-graded material with larger grains (0-200 mm) compared to a uniformly graded sand with grain size 0-2 mm. The main challenge with the laboratory testing was handling the large amounts of soil material needed for each sample, making it difficult to control the initial void ratio. This is a drawback when analysing the deformation behaviour of the tests. The general behaviour was that the samples underwent initially contraction, which ended with dilatancy and most test reached net increase of volume by the end ofthe shearing.

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  • 4.
    Do, Tan Manh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Excess pore water pressure generation in fine granular materials under cyclic loading -A laboratory study2021Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Abstract Excess pore water pressure can be generated in subgrades of both railway and pavement sub-structures under cyclic loading caused by heavy traffic. When saturated subgrades are subjected to cyclic loading, excess pore water pressures accumulate over time which then could lead to migration of particles into overlying layers. The migration of subgrade soil particles to the upper layers would lead to clogging of pores and reducing the upper layers' drainage capacity. Both excess pore water pressure accumulation and migration of fine particles could negatively affect the long-term performance and service life of the sub-structures and eventually may lead to failure. Understanding the mechanism of both excess pore water pressure and migration of fine particles under cyclic loading is, therefore, essential for not only designing but also further proposing efficient and economical maintenance methods. The main objectives of this research are to (1) investigate excess pore water pressure generation in fine granular materials under cyclic loading and (2) evaluate migration of fine granular materials into overlying layers under cyclic loading.  A series of undrained cyclic triaxial tests were performed to study the excess pore water pressure generation in fine granular materials. Two types of fine granular materials, i.e., railway sand (natural granular material) and tailings (artificial granular material), were selected for this investigation. The cyclic characteristics of these materials, e.g., accumulated strain and excess pore water pressure, were evaluated in terms of number of cycles and applied cyclic stress ratios (CSR). As a result, axial strain and excess pore water pressure accumulated over time due to cyclic loading. However, its accumulations were significantly dependent on CSR values and material types. Finally, a relationship between excess pore water pressure and accumulated strain of the fine granular materials was discovered based on all outputs from the undrained cyclic triaxial tests (both tailings and railway sand samples).  In order to evaluate the migration of fine granular materials into overlying layers under cyclic loading, a modified large-scale triaxial system was used as a physical model test. Samples prepared for the modified large-scale triaxial system composed of a 60 mm thick gravel layer overlying a 120 mm thick subgrade layer (tailings and railway sand). The quantitative analysis on migration of the fine granular materials was based on the mass percentage and grain size of migrated materials collected at the gravel layer. In addition, the cyclic responses (strain and pore water pressure) were evaluated. As a result, the total migration rate of the railway sand sample was found to be small. There were no migrated sand particles pumped up to the gravel surface, i.e., no mud pumping, after the test terminated. The migrated sand particles were observed and collected at the bottom half of the gravel layer. The total migration rate of the tailing sample was much higher than that of the railway sand sample. In addition, the migration analysis revealed that finer tailings particles tended to be migrated into the upper gravel layer easier than coarser ones under cyclic loading. The migrated tailings particles were observed at the surface of the gravel layer after the test ended. It could be involved in significant increases in excess pore water pressure at the last cycles of the physical model test. The findings obtained in this research may provide an additional contribution to the literature dealing with the excess pore water pressure accumulation and its effects on the migration of fine particles under cyclic loading. 

  • 5.
    Bansal, Tarun
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Frost line under road embankments: Impact of snow in ditches2021Licentiate thesis, comprehensive summary (Other academic)
  • 6.
    Majala, Jonas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Interpretation of Railway Track Alignment Measurements in a Geodynamic Perspective2021Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development in society means that infrastructure like ballasted railway systems are facing challenges due to request for increased number of high-speed trains and heavier freight trains. This implies that ballasted railways get an increased impact from larger dynamic loads. The question is how the ballasted railways are today affected by dynamic loading and how will an increase in train speed and weight change the soil behaviour within the railway embankment.  A method of investigating dynamic soil behaviour is via geophysical measurements. Accelerometers are commonly used for vibration measurements and by installing them on trains are measurements possible to perform for complete railway sections. The knowledge of expected natural frequencies for various track components and soil layers are essential when considering frequency based analysis of vibration measurements. Thus, a frequency based analysis of accelerometer measurements from track recording coaches enables a possible method for analysing the impact of dynamic loads on underlying soil materials with means of a knowledge of expected natural frequencies for various track components and soil layers. Importance to study frequency content of ground motions became more relevant after the Mexico City earthquake 1985 i.e. studies on this specific earthquake revealed amplification of ground motions due to a long duration of shaking and resonance of soil deposits and furthermore causing damage to buildings whose natural period was the same as the period of ground motion. Thus, if we consider a railway with long train sets running along the railway line. Long durations of shaking of the ground can occur as well as a possible resonance of various soil layers leading to changes in material properties. An interesting finding regarding vibration measurements conducted on a track recording coach show that after Fast Fourier Transformation of the measured vibration data, a frequency spectrum analysis indicate possibilities to detect resonance of the ballast layer in the railway embankment. Therefore, this thesis focus on frequency based analysis of the ballast layer were indications of changes in shear modulus of ballast is seen with means of frequency spectrum and theoretical knowledge of the change in shear modulus in ballast material under cyclic loading and increased shear strain. The thesis consists of two main parts, first is the construction of the so-called frequency-based analysis method of track alignment measurements in a geodynamic perspective and the second part is application of the frequency-based method on a case study. Thus, the scientific contribution of this thesis is to increase knowledge of track alignment measurements in the geotechnical field and to provide a frequency based analysis method of track alignment measurements in a geodynamic perspective for evaluation of soil properties. For the actual case study two different railway sections in Sweden is chosen to enable a comparison, especially when these sections differ with respect to one having only a ballast layer and subgrade and one having ballast, sub ballast and subgrade. Thus, the section with only ballast and subgrade enable a clearer analysis since these layers have large difference in natural frequency. First section is located at Tolikberget in the north part of Sweden and second one between Stenkumla and Dunsjö in south of Sweden. From the analysis of the selected sections it is possible to see indications from the frequency spectrum that the vibration measurements capture the natural frequencies of ballast material associated to the maximum shear modulus and to varying degrees of reduced shear modulus due to increased shear strain. Thus, it can be concluded that vibration measurements conducted on track recording coaches have potential to be used for studies of changes in ballast materials dynamic properties.    

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  • 7.
    Tommik, Karina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Thermal balance inside culverts subjected to seasonal frost for determination of frost depth2021Licentiate thesis, comprehensive summary (Other academic)
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  • 8.
    Silva, Ingrid
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Suffusion of Glacial Till Dam Cores: An Experimental Investigation2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Suffusion, also called internal instability, is an internal erosion mechanism that occurs in embankment dams when fine-grained particles are washed out of the core soil matrix by seepage. Initiation of internal erosion depends mainly on three major factors: grain size distribution of the soil, stress conditions and hydraulic load; whilst its continuation depends of the filter properties. Broadly graded moraines, as glacial tills, are more susceptible to internal erosion by suffusion than other types of soils used in dams.

    Most embankment dams in Sweden consist of a central core of glacial till built more than 50 years ago. At the time of its construction, the available guidelines did not include specific grain size boundaries for the core and the filter related to internal erosion susceptibility. Today, several Swedish embankment dams have experienced incident of internal erosion such as leakages and sinkholes, making internal erosion an important safety issue. This circumstance allows raising the questions: How safe are the Swedish embankment dams and what conditions are needed for internal erosion by suffusion to initiate?

    This research aims to contribute to the assessment of dam safety by giving inputs regarding the characterization of internal erosion by suffusion and the relation among the main factors involved on its occurrence (geotechnical characteristics of soil material, degree of compaction and hydraulic load). This in order to increase the knowledge regarding the critical hydraulic gradient needed to develop suffusion in a given till material with a known degree of compaction.

    The research includes a laboratory program consistent on suffusion tests, which is an extension of the standard permeability test, and considers post-test examination and diagnosis of the samples. Two main groups of tests were performed: small and large suffusion tests. The small tests serve as a reference of the expected behaviour of soil samples under different boundary and test conditions, which allows optimizing the number of test to be performed in large tests.

    Results show that suffusion mechanism can be classified as internal suffusion (or filtration) and external suffusion (loss of soil particles from the soil matrix). The influence of compaction degree on the initiation of suffusion is limited in internally stable soils. However, poorly compacted specimens exposed to high hydraulic gradients could develop both internal and external suffusion if the filter is not capable to retain the eroded particles. The hydraulic conductivity of specimens with internal suffusion tends to decrease with a step wise increase of the hydraulic gradient. Such tendency is the result of the matrix of soil reaching equilibrium with the new seepage stresses. The hydraulic conductivity of specimens with external suffusion tends to increase with the increase of the hydraulic gradient.

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  • 9.
    Rothhämel, Mirja
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Near-surface soil stabilisation to reduce the frost susceptibility of soft soils2018Licentiate thesis, comprehensive summary (Other academic)
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  • 10.
    Toromanovic, Jasmina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    On Parameter Identification for Better Predictions of Dam Behaviour2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Numerical modelling is often needed as a tool to predict the behaviour and assess the safety of dam structures. Embankment dam structures analyses are quite complex and potential failures are hazardous. Predictions of dam behaviour by numerical modelling rely on knowledge about the mechanical properties of the materials the dam is constructed with. The materials included in a dam vary significantly because zones in the dam have different functions. In order to conduct reliable modelling, parameter values defining the stress-strain relationship of the materials are needed to be assigned.

     Obtaining information about the mechanical behaviour in already existing embankment dams is usually challenging. As many dams are old, there might be a limited amount of information available of the materials used, construction methods and mostly about the stress-strain relationship of the soil. Traditionally, field sampling is performed in order to obtain such information. However, conventional field sampling might negatively affect the dam body and thereby the performance as well as the safety of the dam. This is of special importance if sampling is performed in the impervious (core) part. Since traditional sampling might harm the dam body, use of non-destructive methods would be advantageous to utilise for obtaining information about the stress-strain relationship and the strength in a dam structure.

     An option for a non-destructive method is parameter identification by inverse analysis. The idea of inverse analysis is to calibrate finite element models towards field measurements. In the calibration process, the input for a stress-strain relationship (constitutive model) is modified until the discrepancy between the output of the numerical model and the associated chosen field measurement is minimised. The agreement between output from the numerical model and reality is measured by an objective function that will calculate the error. In order to automatically search for the minimum a search algorithm is utilised in the optimisation process. When the objective function is minimised, the calibration of the material parameters is done.

     In previous research at Luleå University of Technology, the method of inverse analysis was applied to an embankment dam. The finite element program PLAXIS was used in combination with an optimisation code. The optimisation code includes an objective function (for error evaluation) and a search algorithm. The genetic algorithm was employed as search algorithm, since it is known for its robustness and efficiency as well as the fact that it provides a set of solutions instead of one unique answer. This is beneficial from a geotechnical point of view, since engineering judgement can be included in the final choice of solution.   

     The first study in the present thesis deals with a case study of an embankment dam, where a simple model calibration was performed. This was a part of a larger study, at the ICOLD Benchmark Workshop in 2017, where the work presented here was forming one of the contributions. In order to have a model response similar to reality, the contributors were asked to choose constitutive models and calibrate them. The calibration was done by manually changing the input for the constitutive model chosen. While the response of the numerical finite element model was capturing the trends of measured total stresses and pore pressure in the dam quite well, there were difficulties in capturing the long term deformations of the dam. This was a challenge for all contributors. An idea for improving the model response, is to run a more advanced calibration by inverse analysis.

     In the second study in the thesis, predictions are presented for the embankment dam that inverse analysis was previously conducted for at LTU. Strengthening actions in form of a new berm were performed at the dam. With identified material parameter values from the inverse analysis, predictions were conducted both before and after the strengthening measures. The predicted deformations were compared to deformation data from inclinometer measurements.  A reasonably well agreement was obtained with the real deformations. The trend of the deformations was replicated and the magnitudes of the deformations were in the right order. The study is indicating that predicting future dam behaviour based on results from inverse analysis can be done reasonably well.

     In the third and final study in the thesis, effects of random measurement error on the performance of the genetic algorithm for soil parameter identification are assessed. Also here, with the application to the embankment dam used in previous research at LTU. Optimisations were performed against inclinometer measurements. To be sure that the constitutive model can find the correct solution, synthetic (i.e. numerically generated) inclinometer data was utilised. Perturbations were randomly generated within chosen intervals of error and added to the numerically generated deformations.

     The genetic algorithm showed its robustness, by continuing to search for solutions without breaking down even if the field data was substantially perturbed. Considering usual errors for inclinometer measurements, the genetic algorithm can deliver good solutions. The inclinometer errors used were taken from literature, and thereafter related to the perturbations of the numerically generated data. Dealing with errors that are becoming gradually larger than what can be considered as usual, problems are faced by the genetic algorithm. In this cases it is difficult to find a solution, and if solutions are found they might significantly deviate from the unperturbed optimum solution.

     The three studies handled in this thesis are treating aspects of back analysis of embankment dams; from a simple calibration, to predictions based on material parameters from advanced inverse analysis and finally effects of errors on the genetic algorithm. It been shown that using inverse analysis for already existing embankment dams is very beneficial for the material characterisation and is forming a step towards better predictions of future dam behaviour.

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  • 11.
    Zeinali, Amin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Thaw Mechanism in Subgrades2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Freezing-thawing, changes the properties of soil due to the phase change of the water in the soil body. Freezing-thawing cycles in the soil have been studied for several decades including extensive laboratory research. In this study, the main focus is thawing based on laboratory investigation. The soil used in the laboratory study is taken from a minor road where an additional field study has been carried out.

    A freezing-thawing laboratory apparatus is manufactured and used in order to get better understanding of the freezing-thawing process. The apparatus is designed for cylindrical sample, one dimensional heat flow, freezing/thawing from top to bottom, water supply from bottom (access to external water) and possible to apply overburden load.

    he laboratory tests were conducted at similar soil samples at different boundary conditions. Water is liberated in the thawing zone of the sample. During thawing the only drainage path is to the surface, however, water migrates upwards even when entire soil is thawed. Upwards water migration after thawing period can be due to the changes in thawed soil properties such as permeability and fine particles redistribution. The rate of thawing is a very important factor for thawing conditions. At low thawing rate the drainage capacity of sample is sufficient to drain the liberated water from ice. Moreover, freezing condition i.e. access to water, has high impact on thawing process. If the volume of ice lenses is high,the thawed soil fluidizes as the water migrates upwards. Pore pressure transducers will be added to the apparatus for further investigation regarding both freezing and thawing.

    The field study has been conducted in order to study thaw behavior in low volume road embankment. The scope of the study is to investigate the thaw weakening progress by Falling Weight Deflectometer (FWD) and Dynamic Cone Penetration (DCP) tests on low volume embankment road near Luleå,northern Sweden. The results from methods is compared and the differences in how they are capturing the thawing is discussed. DCP which is known as an easy and cheap method to estimate stiffness of soil layers is applied to estimate thawing period and the layer which thaw weakening takes place at. Stiffness gained by back calculation of FWD results which is performed on the same road embankment and same period of time DCP test is done.

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  • 12.
    Abdullah, Twana
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Groundwater Vulnerability Using DRASTIC model Applied to Halabja Saidsadiq Basin, IRAQ2017Licentiate thesis, comprehensive summary (Other academic)
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  • 13.
    Dagli, Deniz
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratory Investigations of Frost Action Mechanisms in Soils2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils.

    Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments.

    Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave.

    Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms.

    Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted.

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  • 14.
    Al-Jabban, Wathiq
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Soil Modification By Adding Small Amounts of Soil Stabilizers: Impact of Portland Cement and the Industrial By-Product Petrit T2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis presents results of laboratory experiments regarding the effectiveness of adding small amounts of binders in order to modify and improve the mechanical performance of low organic clayey silt soil. Two types of binders have been used i.e. cement and an industrial by-product named Petrit T. The study covered both the immediate and longterm effects on the soil material. Binder content was added by soil dry weight, Petrit T at 2, 4 and 7% and cement at 1, 2, 4 and 7%. An experimental program has been carried out, including tests of consistency limits, unconfined compressive strength, density, solidification, grain size distribution (by laser particle size analyzer) and pH. The tests were conducted on the treated soil with varying binder contents and after different curing periods, i.e. after 7, 14, 28, 60 and 90 days. Results show that cement is more effective in improving the physical and engineering properties than Petrit T. Plasticity index decreases after treatment and leads to an immediate increase in workability. This is found directly after treatment and it increases with time. Soil density increased, whilst water content decreased, with increasing binder content and curing time. Particle size distribution of soil is changed toward the granular side by the reduction of the particles in clay size fraction and increasing silt size particles after 28 days of treatment. Both binder types resulted in an immediate effect on the soil pH value. This value increased to 12.3 after adding 7% of the binder and then it gradually decreased as curing time increased. The cement treated soil exhibits a more brittle failure behavior than the soil treated with Petrit T. In this case a more ductile behavior was observed. The findings confirmed that adding small binder contents of cement and by-product Petrit T significantly improved the physical and mechanical properties of soil, which can contribute to reduce the environmental threats and costs that are associated with using high binder contents in various construction projects.

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  • 15.
    Chabuk, Ali Jalil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Analysis of Landfill Site Selection-Case Studies Al-Hillah and Al-Qasim Qadhaas, Babylon, Iraq2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The selection of a landfill site is considered as a complicated task because the whole process is based on many factors and restrictions. This study shows the present status of solid waste management, solid waste sources, staffing for solid waste collection, machinery and equipment used in the waste collection process, finance and financial management at Babylon Governorate and its Qadhaa. The management of collection and disposal of waste in Babylon Governorate and its Qadhaa is done through open dumping of waste and the quality of the collection process is poor. This is the case in Al-Hillah Qadhaa, which is located in the central part of the governorate, Iraq and Al-Qasim Qadhaas, which is situated in the southern part of the Babylon Governorate, Iraq. These sites do not conform to the scientific and environmental criteria applied in the selection of landfill sites. 

    In the first part of the current study, to find out how much solid waste will be produced in the future; two methods were used to calculate the population growth in Al-Hillah and Al-Qasim Qadhaas to the year 2030. The results showed that the total waste in 2030 according to the first and second methods respectively will be 394,081 tonnes and 472,474 tonnes in Al-Hillah Qadhaa, and (54,481 tonnes and 76,374 tonnes) in Al-Qasim Qadhaa. The cumulated quantity of solid waste expected to be produced between 2020 and 2030 according to the first and second methods respectively was 3,757,387 tonnes and 4,300,864 tonnes in Al-Hillah Qadhaa, whilst in Al-Qasim Qadhaa it was 519,456 tonnes and 695,219 tonnes. The generation rate in 2020 will be (0.88 and 0.62) kg/ (capita. day) in Al-Hillah and Al-Qasim Qadhaas respectively; in year 2030, the generation rate will be (0.97 and 0.69) kg/ (capita. day) based on method 2 and an expected incremental increase in generation rate of 1 kg/ (capita. day) per year. 

    The second part of this study aims to find the best sites for landfills in Al-Hillah and Al-Qasim Qadhaas. For this reason, 15 criteria were adopted in this study (groundwater depth, rivers, soil types, agricultural land use, land use, elevation, slope, gas pipelines, oil pipelines, power lines, roads, railways, urban centres, villages and archaeological sites) using GIS (geographic information system), which has a large capacity for managing input data. In addition, the AHP (analytical hierarchy process) method was used to derive the relative weightings for each criterion using pairwise comparison. The suitability index map for candidate landfill sites was obtained. Two suitable candidate landfill sites were found to fulfill the scientific and environmental requirements in each Qadhaa, with areas of 9.153 km2 and 8.204 km2 respectively in Al-Hillah Qadhaa, and with areas of 2.766 km2 and 2.055 km2 respectively in Al-Qasim Qadhaa. The area of these sites can accommodate solid waste from 2020 until 2030 based on the required areas, which were 4.175 km2 and 4.778 km2 (Ali-Hillah Qadhaa) and 0.577 km2 and 0.772 km2 in (Al-Qasim Qadhaa) according to the first and second methods respectively.

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  • 16.
    Magnusson, Simon
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Environmental Perspectives on Urban Material Stocks used in Construction: Granular Materials2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The peoples demand of functions and services in cities is the driver for energy and material flows. Most people in the world are now living in urban areas. In order to achieve a sustainable development of cities, both resource use and environmental impact have to be reduced. For construction activities, an important aspect is to increase the reuse of construction materials. From a resource perspective, the urban demand for construction of buildings, infrastructure and other facilities results in materials accumulated in constructions but also in other applications and in landfills. The materials can be described as the urban material stock where some materials are used and others are not used, i.e. wasted. There are many cases where material stocks are used for construction purposes. For example, used concrete and bricks, excavated soil and rock from construction projects and other wasted materials such as rubber from tires can be crushed, shredded and sorted to granules and used in many different construction applications. Different perspectives can be applied when assessing the environmental impacts of using stocked material in construction. The overall aim of this thesis is to study the environmental impacts of using granular soil, rock and rubber in construction. For soil and rock, the aim is to study the environmental impact of material management in urban areas. For granular rubber, the aim is to study the environmental impact of artificial turf from a life cycle perspective and from different infill materials of recycled and new rubber and plastics. 

    The literature of excavated soil and rock was reviewed in order to identify and quantify the material flows and greenhouse gas (GHG) emissions from the management of soil and rock materials. For artificial turf and the different infill materials, a life cycle approach was used to quantify the energy use and GHG emissions. A chemical analysis of potential chemical leaching from the different infill materials to water was conducted in order to compare potential local emissions to water. 

    Based on the results, it was concluded that the knowledge about the urban flows of excavated soil and rock is lacking in terms of patterns, quantities, qualities and its environmental performance. A resource perspective is missing in the literature. However, the recycling of soil and rock can reduce resource use and GHG emissions. It was suggested that models are developed that take into account future material demand and availability to soils and rock. From such information it would be able to assess sustainable management practices and the possibilities of sharing materials between urban construction projects in order to reduce resource use and environmental impact. 

    It was concluded that for the life cycle of artificial turf, the production of construction materials contributes largely to energy use and GHG emissions. Differences in terms of energy use and GHG emissions for the production of infill materials are large. The production of new material required more energy and resulted in more GHG emissions than using recycled rubber. The potential release of substances from infill materials to water were shown to be possible for all infill materials analyzed. Previous assessments of local environmental impacts of using infills generally concludes that the impacts are small. These assessments are primarily focused on infill of recycled tires. It is therefore concluded that environmental assessments of local impact should include all infill types. 

    Environmental assessments of using stocked materials in construction should take into consideration the material applications´ significance for the environmental impacts at a higher system level. Broader system boundaries in environmental assessments will reduce the risk for sub-optimizations when taking decisions on how materials should be used in construction. 

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  • 17.
    Yang, Ting
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Borehole sealing with expandable buffer clays in HLW disposal: Lab-scale performance2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two basically different multibarrier concepts for high-level radioactive waste (HLW) are the often cited KBS-3 V/H concepts, for isolating nuclear waste at 400-600 m depth and Very Deep Boreholes concepts (VDH) for placement at 2000-4000 m depth. Both make use of expandable clay as isolating medium of canisters with HLW and as backfill material in shafts and tunnels in repositories for safe disposal of such waste. This licentiate thesis is based on three papers related to the properties of clays for use as engineered barriers, and to their performance at geological disposal. The first paper deals with the buffer criteria for the two disposal concepts. In this paper the possibilities and limitations of using clays of montmorillonite-, saponite- and mixed layer clay type are considered. The second paper discusses the swelling property and permeability of Na-montmorillonite clays (MX-80, GMZ) and illite-smectite mixed layer clay (Holmehus) saturated and percolated by distilled water and a salt solution. The third paper describes a lab-scale performance of VDH holes sealing using Holmehus clay. In this paper, methods for solving the problem of too quick hydration of the dense clay are investigated and evaluated.

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  • 18.
    Knutsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Tailings Dam Performance: Modeling and Safety Analysis of a Tailings dam2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Storage and management of mine waste are both needed in the mining industry. After mineral extraction of the ore, there are generally leftovers with insufficient economical value that need to be taken care of. The finest grained fractions are referred to as tailings. Since every mine site and every tailings impoundment is unique, there is unfortunately not an universal answer to proper management that can be applied everywhere. Even though local guidelines and regulations can be considered to give a best practice in terms of design, there is correspondingly a need for dam safety stewardship on an operational level. Without such stewardship, not even the best designed dams or facilities would be fully controlled in terms of safety. Conversely, even badly designed dams can be operated in safe manners with good stewardship and surveillance programs. The coupling between design and stewardship is therefore important in order to reach proper tailingsmanagement.In the design of tailings dams, a certain value of the factor of safety for slopes of the dams is normally striven for to secure stability. The value is generally based on national regulations and/or guidelines. In Sweden the factor of safety should not be lower than 1.5 under normal conditions. In the guidelines, recommendations are often given on dam surveillance and field measurements of e.g. pore water pressure, deformations and seepage. Field measurements are taken, but are generally assessed in terms of trends (change with time) and not by comparison to anticipated performance.In this study, numerical modeling has been used for stability analyses and dam performance, as predictions of deformations and pore water pressure levels. An upstream tailings dam located in northern Sweden has been used as a case. The granular materials being part of the model based were described based upon geotechnical investigations (field and lab). The tailings material was modeled, on a constitutive level, by the Hardening Soil model. Good agreement betweensimulated behavior and laboratory tests was achieved. Other dam materials were simulated by the Mohr-Coulomb model.The model was built as a staged construction model where historical events between 1992 and 2013 were simulated. The historical events included dam raises, increased beach elevations, remedial works etc. The simulations of historical events were used for facilitating comparison with field measurements. By means of inclinometer data, horizontal deformations were measured and evaluated for a period of six years. These deformations were accurately simulated, which was considered to verify the numerical model. By this verification, the model is considered accurate enough to be used for simulating future events. Both stability and corresponding dam performance were computed, by simulating a period of 10 years. The stability analyses were used for the set-up of rockfill support plans, i.e. where and when remedial works are needed in order to maintain a certain safety level. The corresponding values in deformations and pore water pressures were used for the set-up of alert levels for each measuring unit. These alert levels will help the engineer in field with data interpretation, where the simulated values are compared with field measurements taken. The proposed methodology is recommended for tailings dams in general, which reduces the gap between design and stewardship. Hence, one step closer to proper tailings management is taken.

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  • 19.
    Vahdati, Pooya
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Identification of soil parameters in an embankment dam by mathematical optimization2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The finite element method (FEM) has been widely used to analyse earth and rockfill dams. In a finite element analysis a proper constitutive model has to be chosen for each part of the dam in order to simulate the relation between stresses and strains. The zones of an earth and rockfill dam have different functions. Because of that the zones normally consist of various soil types for which the stress/strain response could vary considerably. For each dam zone, suitable values have to be assigned to the parameters included in the constitutive model chosen. In general, laboratory tests and/or field tests of the soil are needed as a basis for this parameter evaluation. However, many dams are old and limited information might be available regarding the soil materials being used in the dam structures. In dams, it is normally very difficult to take up soil samples for testing, especially from the central impervious part, since this might affect the dam performance and the safety of the dam. For dams it would be advantageous if constitutive parameter values could be determined with some non-destructive method. Inverse analysis provides a possibility to determine the constitutive behaviour of different materials within the dam structure under the condition that the dams have been equipped with various instrumentations, for monitoring dam performance, which record data such as pore pressures, deformations, total stresses and seepage etc. In the method of inverse analysis, two separate parts are included: (1) an optimization method consisting of an error function and a search algorithm and (2) a numerical method to solve the partial differential equations arising in stress-strain analysis of structures. In this study, inverse analysis of a dam case was performed with a commercial finite element program Plaxis and the genetic algorithm was utilized as the search algorithm in the optimization method. The genetic algorithm was chosen due to its robustness and efficiency, particularly since it provides a set of solutions close to the optimum solution instead of one unique answer; a set of solutions is more practical from a geotechnical perspective. In the proposed inverse analysis a finite element model is calibrated automatically by changing the values of the input parameters of the selected constitutive model in different dam zones until the discrepancy between the measured results by dam instrumentations and the corresponding computed results is minimized.In order to examine the efficiency and robustness of the genetic algorithm, the research was initially focused on a synthetic case study. The synthetic case, a set of model parameters known in advance, is a good test of the mathematical basis used in the optimization, i.e. the objective function and the search algorithm. The Mohr-Coulomb model was chosen for all dam zones, as an initial choice for this research, chiefly because of its simplicity. A very good agreement for the optimization against the synthetic case was obtained. The practical outcome of an inverse analysis clearly depends on the ability of the constitutive models chosen to capture the real soil behaviour in the different dam zones. A proper choice of a constitutive model provides an opportunity to calibrate the finite element model properly. Therefore, in the next step the Hardening soil model, an advanced constitutive model, was chosen for optimization on the dam. In this part of the research, two cases (A and B) based on different reservoir water levels and number of berms constructed, were analysed. All the data of horizontal displacement were received from exactly the same positions in the geometry as the measurements carried out with the single inclinometer. The results of inverse analyses showed that the Hardening soil model is able to capture better the soil displacements within the dam structure, especially at the crest part, compared to the Mohr-Coulomb model.Finally, it was concluded that inverse analysis is a practical tool for identifying soil material properties of earth and rockfill dams and provides a non-destructive method for dam engineers to obtain more information about the dams. Moreover, if inverse analysis applications become available in commercial finite element software, it would certainly be a valuable tool for dam engineers assessing dam performance and dam safety.

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  • 20.
    Johansson, Jens
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Impact of Water-Level Variations on Slope Stability2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Waterfront-soil slopes are exposed to water-level fluctuations originating from either natural sources, e.g. extreme weather and tides, or from human activities such as watercourse regulation for irrigation, freshwater provision, hydropower production etc. Slope failures and bank erosion is potentially getting trees and other vegetation released along with bank landslides. When floating debris is reaching hydropower stations, there will be immediate risks of adverse loading on constructions, and clogging of spillways; issues directly connected to as well energy production as dam safety.The stability of a soil slope is governed by slope geometries, stress conditions, and soil properties. External water loading, pore-pressure changes, and hydrodynamic impact from water flow are factors being either influencing, or completely governing the actual soil properties. As a part of this study, knowledge concerning water-level fluctuations has been reviewed; sources, geotechnical effects on slopes, and approaches used for modelling, have been focused. It has been found a predominance of research focused on coastal erosion, quantification of sediment production, bio-environmentallyissues connected to flooding, and effects on embankment dams subjected to rapid drawdown. Though, also water-level rise has been shown to significantly influence slope stability. There seems to be a need for further investigations concerning effects of rapidly increased water pressures, loss of negative pore pressures, retrogressive failure development, and long-term effects of recurring rise-drawdown cycling.Transient water flow within soil structures affects pore-pressure conditions, strength, and deformation behavior of the soil. This in turn does potentially lead to soil-materialmigration, i.e. erosion. This process is typically considered in the context of embankment dams. Despite the effects of transient water flow, the use of simple limitequilibrium methods for slope analysis is still widely spread. Though, improved accessibility of high computer capacity allows for more and more advanced analyses to be carried out. In addition, optimized designs and constructions are increasingly demanded, meaning less conservative design approaches being desired. This is not atleast linked to economic as environmental aspects. One non-conservative view ofslope-stability analysis regards consideration of negative pore pressures in unsaturated soils. In this study, three different approaches used for hydro-mechanical coupling in FEM-modelling of slope stability, were evaluated. A fictive slope consisting of a wellgraded postglacial till was exposed to a series of water-level fluctuation cycles. Modelling based on classical theories of dry/fully saturated soil conditions, was put against two more advanced approaches with unsaturated-soil behavior considered. In the classical modelling, computations of pore-pressures and deformations were run separately, whereas the advanced approaches did allow for computations of porepressures and deformation to be fully coupled. The evaluation was carried out by comparing results concerning stability, vertical displacements, pore pressures, flow, and model-parameter influence. It was found that the more advanced approaches used did capture variations of pore pressures and flow to a higher degree than did the classical, more simple approach. Classical modelling resulted in smaller vertical displacements and smoother porepressure and flow developments. Flow patterns, changes of soil density governed by suction fluctuations, and changes of hydraulic conductivity, are all factors governing as well water-transport (e.g. dissipation of excess pore pressures) as soil-material transport(e.g. susceptibility to internal erosion to be initiated and/or continued). Therefore, the results obtained underline the strengths of sophisticated modelling.

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  • 21.
    Bhanbhro, Riaz
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical Properties of Tailings: Basic Description of a Tailings Material from Sweden2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Tailings dams are constructed to store waste material from mining industry and usually these dams are raised with time depending upon production rate. Tailings material is sometimes used in construction of tailings dams. Tailings are artificial material and the behavior of tailings material upon loading is different compared to natural soil materials. The mechanical properties of tailings have influence on the performance of a tailing dam. Since the tailings dams are constructed to withstand for long times, it is essential to understand tailings materials in depth in order to assure safe existence of the dams in short term as well as in long term perspective. This licentiate thesis describes the present work carried out on sulphide rich tailings from one mine in Sweden. The material presented is based upon material from three different papers. The first paper describes the basic characteristics of tailings which includes; specific gravity, phase relationships, particle size, particle shape and direct shear behavior. The second paper discusses direct shear tests carried out on tailings from one Swedish mine. Shear strength parameters are evaluated and results from 27 tests (15 drained and 12 undrained tests) are discussed. This paper also describes the vertical height reductions observed during direct shear tests. The third paper focuses on the laboratory results from triaxial tests conducted on tailings materials. This paper shows the drained behavior of tailings under application of different consolidation pressures.The results from particle analysis showed that smaller particles were very angular and bigger particles were sub angular. The material was classified as silt and silty sand. The average particle density (ρs) is 2.83t/m3. The dry density and void ratios were found to be 1.18–1.65 t/m3 and 0.72–1.41 respectively. During direct shear tests vertical height reductions were observed with slight increment in pore pressures. The strain hardening behavior was observed in both drained and undrained conditions in direct shear tests. The strength parameters determined in triaxial test were higher than of those calculated in direct shear tests. Friction angle ϕ' in triaxial tests were found to be 39 to 41degrees and it did not showed any effect with relation to depth. The cohesion and friction angle in direct shear test at 0.15radian, in drained tests were found as in range of 9.7-33.7kPa and 12.5-18.3 degrees respectively. The same parameters for undrained tests were found as 7.1-16.1 kPa and 16.0-20.4 degrees for cohesion and friction angle respectively.

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  • 22.
    Mårtensson, Stefan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Svenska offpistskidåkares förutsättningar att hantera lavinfara: Individuella och kontextuella faktorers påverkan på risktagandet2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Every winter die statistically, two to three Swedes in avalanche accidents. Approximately eight out of ten are killed abroad even though only one out of eight Swedes skis outside Sweden. Swedes seem to die in a greater extent than other nationalities abroad. It is not possible to find similar trends in other nationalities mortality in avalanche accidents in skiing abroad.Why do Swedes die in a greater extent than other nationalities when skiing abroad? The overarching question is broken down into two parts. Firstly which are the Swedish off-piste skier’s individual abilities to handle avalanche risk? Secondly how does the domestic knowledge and communication environment look like with respect to avalanche risk?No previous studies have addressed the relationship between individual and contextual factors on management of avalanche risk in a foreign environment. Possible causes of avalanche accidents are described in the literature, with a focus on individual factors.Four studies were conducted to describe the Swedish off-piste skier's individual and contextual factors associated with the handling avalanche risk. The first study was a web-based questionnaire about the experience, knowledge, attitude to risk, and more. The second study was a statistical analysis of the Swedish public avalanche danger ratings during ten years. The third study was a literature review of Swedish avalanche literature from 1943 onwards. The last and fourth study was an online survey with questions about access, quality and relevance, and more with regard to Swedish avalanche communication.The various studies were triangulated with respect to data and methodology in relation to a number of research questions, formulated on the basis of the relationship between perception and preparation on one hand and the experience and trust on the other. The results showed a consistent picture of both individual, and contextual variables. The studies describe Swedish off-piste skiers as experienced, trained, prepared and risk aware. The contextual study showed that the Swedish public avalanche communication is of autonomous nature, hard to find, mostly irrelevant and of uncertain quality and origin.Overall, this work has revealed a possible explanation model that needs to be explored in more detail with respect to how the Swedish off-piste skier's mental models can be described and how Swedish public communication about avalanches should be changed to reduce future mortality abroad among Swedish off-piste skiers.

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  • 23.
    Al-Taie, Entidhar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Foundations of educational buildings in Iraq: past, present and future2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Foundation is considered as one of the main parts of any structure such as buildings, railways, bridges, etc. The type of foundation used is highly dependent on the type and properties of soil. The design of foundations requires many factors that should be defined such as the load that the foundation is going to hold, geological conditions of the soil under the foundation, type of soil and the local building code criteria.There are number of differences in the geological and soil conditions in Iraq. As a consequence, these differences are reflected on the type of foundation to be used. Despite these differences, same materials and style of buildings are used all over Iraq. To have good information about the materials and the required design of the foundation, a comprehensive historical review was executed to highlight the progress of the materials and types of foundation that was used since the dawn of civilization up to the present (ancient, Islamic, Ottoman and British occupation till after independent). Present day situation had been analysed through a case study which illustrated the link between soil and foundation types in three different parts of Iraq (Mosul, Baghdad and Basrah). One building was analysed using STAAD. Pro software in these regions. Furthermore, the same building was analysed using local materials, which were historically used and was compared with present day materials used.It is evident that Iraqi designers and engineers require local code to define all the loads, materials and design of the foundation to be used. The use of local materials might be very effective from both engineering and economic perspectives.

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  • 24.
    Rodriguez, Juan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Importance of the particle shape on mechanical properties of soil materials2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Particle shape of soil aggregates is known to influence several engineering properties; such as the internal friction angle, the permeability, etc. Even if this is known, there has been only minor progress in explaining the processes behind its performance and has only partly implemented in practical geotechnical analysis. Previously shape classification of aggregates has mainly been performed by ocular inspection and e.g. by sequential sieving. In geotechnical analysis has been a lack of an objective and rational methodology to classify shape properties by quantitative measures. The image analysis, as quantitative methodology, is tested and it is investigated how the results are affected by resolution, magnification level and type of shape describing quantity. Tailings as a part of granular materials need to be stored safely in facilities and for a long time perspective a good knowledge of current and future materials properties is needed. Tailings are site specific and not well investigated compare to natural geological materials. There also is a need of prognosis tools for long term behavior. Based on laboratory test tailings from Aitik mine has been investigated through triaxial test and particle shape (using two dimensions image analysis).The overview has shown that there is no agreement on the usage of the descriptors and is not clear which descriptor is the best. The resolution in the processed image needs to be considered since it influences descriptors such as e.g. the perimeter. Recent development in image analysis processing has opened up for classification of particles by shape. The interpreted results show that image analysis is a promising methodology for particle shape classification. Results are affected by the image acquisition procedure, the image processing, and the choice of quantity, there is a need to establish a methodology to ensure the objectivity in the particle shape classification. A comparison between laboratory shear strength tests of the analysed tailings material and previously published empirical relationships between shape and friction angle indicates that the minimum quantity value have the shortest difference between obtained data and expected results.

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  • 25.
    Lintzén, Nina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical properties of artificial snow2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mechanical properties of snow have been a subject of research since the mid-20th century. Theresearch done is based on natural snow. During the last decades the winter business industryhas been growing and also the interest for constructing buildings and artwork of snow. Suchconstructions are generally built using artificial snow, i.e. snow produced by snow guns. Up tothe present constructions of snow are designed based on knowledge by experience. Only minorscientific studies on artificial snow and its properties has been published. Hence it is ofimportance to investigate material properties for artificial snow.A survey of current state of the art knowledge of properties for natural snow was done andbasic material properties for different qualities of artificial snow were investigated. Strengthand deformation properties for artificial snow were evaluated through uniaxial compressivetests where cylindrical test specimens were subjected to different constant deformation rates.The results show that artificial snow at low deformation rates will have a plastic deformationbehavior where the initial deformation will cause a hardening of the snow structure. At higherdeformation rates brittle failure may occur. For artificial snow with a homogeneous and finegrained structure the deformation behavior was found to change from plasticity to brittleness ata certain critical deformation rate. Artificial snow with coarse grained structure was found to bebrittle giving unstructured results independent of the load level.Four point loading was applied on beams of artificial snow to study creep deformation, bendingstrength and to determine the ultimate load for the different snow qualities. The results showedcoarse grained artificial snow underwent relatively small creep deformations. Both the creepbehavior and the ultimate strength varied randomly at the same applied load. Large plasticdeformations were observed with the fine grained artificial without any failure of the beams.The ultimate load was relatively high and repeatable results were achieved for all test.Previous presumptions that coarse grained artificial snow with high density would have highstrength and were not confirmed by the experiments performed on different qualities ofartificial snow. The performed tests indicate that fine grained artificial snow of lower densityhave more predictable strength properties of equally high or higher magnitude as for coarsegrained artificial snow. The plastic deformations were however higher for the fine grainedartificial snow. High deformations are not favorable for structures which should maintain theshape during the winter season. When designing constructions of snow both strength anddeformation properties should be taken into account.

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  • 26.
    Makusa, Gregory Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical properties of stabilized dredged sediments: for sustainable geotechnical structures2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dredging activities at Ports and Harbors are inevitable for the safe navigation of ships and vessels. Dredged material may range from very fine and contaminated sediments to sand and gravels. While, granular dredged material can be directly utilized in civil engineering applications, fine sediments may require further treatment before use. In geotechnical context, fine sediments are characterized by low shear strength and high compressibility. However, these unfavorable properties do not rule out the suitability of these fine dredged sediments for use in geotechnical construction, such as, road embankment, building foundation or as structural backfill in land reclamation. Mass stabilization solidification provides a comprehensive technology for amending fine sediments at high initial water content, resulting into construction materials of improved strength and reduced compressibility. The ultimate in-situ soil behavior types, stiffness and strength properties of stabilized mass depend on various factors such as binders, mixing equipment, curing temperature, in-situ boundary conditions and mostly important the applied preloading weight during the period of curing. However, despite improved mechanical properties for geotechnical applications, the performance of treated materials becomes susceptible to repeated freeze-thaw cycles. Understanding geotechnical design process, which includes evaluation of material properties, loading condition and selection of appropriate constitutive model, is an important task for settlement and stability analysis of structures founded on stabilized mass. The selection of suitable material model is vital for successful finite element analysis. Nevertheless, among all existing constitutive soil models, none of them can capture all aspects of soil behavior. Therefore, the meaningful and quantifiable predictions of field behaviors are possible only if, undisturbed samples or in-situ tests are used for determination of mechanical properties, and the predictive capacity of selected constitutive model comes from the comparison with field observations In the present research work, utilization of cone penetration test (CPT) data for evaluating the mechanical properties of stabilized dredged sediments for geotechnical design and analysis was presented. A large-scale field test at the Port of Gävle was utilized as a case study, to verify the simulated settlement of preloaded stabilized dredged sediments. The stabilized mass–soil classification behavior type was studied utilizing CPT classification charts. Computation of the primary consolidation settlement due to preloading weight were carried out in PLAXIS 2D geotechnical software and verified against field measurements. A suggestion to protect the stabilized mass against severe weather condition was discussed.

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  • 27.
    Ali, Ammar Adel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Morphology of Tigris River inside Baghdad City2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Tigris and Euphrates rivers represent the artery of life in Iraq. Tigris River rises from Turkey and flows toward the southeast to enter Iraq. It drains a catchment area of 473 100 km² of which about 58% lies in Iraq. In this study the reach, about 50 km long, of the river inside Baghdad was been studied. It starts at Al-Muthana Bridge and ends at Tigris-Diyala River confluence. Generally, the river reach is part of an alluvial plain, single channel and meandering. The bed material of the river is composed mainly of fine sand and small portion of silt and clay. Other significant features of the reach are the growing islands and bank depositions. Recently water resources of Iraq are negatively affected by climatic changes and the huge water projects in the riparian countries. As a result, the flow of Tigris River at Baghdad city has significantly decreased where the average monthly flow is 520 m³/s for the period 2000-2012 which represents about 50% reduction compared to previous periods. The estimated trend for the average monthly discharges is a reduction of 5.4 % during the last 23 years. Low flow and low water levels have enhanced the water to erode the banks below its protected part. This might affect the future stability of the banks. The drop of the river discharge together with debris from the last wars in 1991 and 2003 enhanced the growing of islands in the river. In this research, changes in the morphology of Tigris River within Baghdad are to be investigated and the causes will be highlighted in order to take the right measures to restore the river system. This is a first step toward studying the hydrological characteristics of the reach. One-dimensional gradually varied flow model, using HEC-RAS, was applied to examine the flood capacity and the possibilities of inundation of the banks. The geometry of the river was represented by the findings from the river survey of 2008. Additional data about the locations and dimensions of the bridges were supplied to the model. The average monthly discharge at Sarai Baghdad for the years 2000-2012 was assumed as the base flow. A range of different scenarios were examined by increasing the discharges in order to determine the critical discharge that may cause inundation. Model calibration was achieved by adjusting the Manning’s roughness coefficient for an observed water surface profile along the lowest part of the reach. The associated error with the computed water surface profiles was in order 0.026m. Additional water level observations at Sarai Baghdad were used for verification purposes. It was found that the discharges higher than 2700 m3/s could cause partial inundation in some areas in the northern part of the reach and these areas extend to approximately 9 km for discharges greater than 3500 m3/s. The southern part of the reach is still safe from inundation for discharges below 3500 m3/s. The slope of water surface profile varies from 6.03 to 10 cm/km for discharges between 400 and 4000 m3/s respectively. In this study, a field survey was conducted between May, 2012 and January, 2013. It involved the installation of 25 bench marks, surveying the upper river banks (from the crest of the stony protection to the water surface) and 250 cross sections. Three kinds of samples were collected at this stage work: (i) river bed material, (ii) suspended load samples and (iii) bed loads samples. Hydraulic measurements were conducted and included water surface elevations, water depths at sampling points, water discharges and transversal velocities. Water temperature and other environmental measurements were also conducted. Particle size distribution, specific gravity and concentration of suspended sediment were executed in the laboratory for the collected samples.

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  • 28.
    Issa, Issa E.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Siltation and sedimentation problem in Mosul reservoir dam2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Iraq depends on the Rivers Tigris and Euphrates for its water resources. Recently the flow of these rivers decreased drastically. In view of this situation the true storage capacity of the dams are to be evaluated to ensure prudent water resources management strategies. In this research, the biggest hydraulic structure in Iraq, Mosul Dam Reservoir, was studied to evaluate its present storage capacity.Mosul dam reservoir is located on the River Tigris in the north of Iraq, 60 km north-west Mosul city. The dam is a multipurpose project for irrigation, flood control and hydropower generation. The storage capacity of its reservoir is 11.11×109 m3 and water surface area is 380 km2 at the maximum operation level 330 m.a.s.l. The dam was operated on July 24th, 1986 and no survey had been conducted to determine its storage capacity since that time. A pre-construction topographic map for the studied area scale 1: 50000 dated 1983 was converted to a triangular irregular network (TIN) format using “Arc/GIS software version 9.3”. The TIN was used to establish the stage-area and stage-storage capacity curves before dam construction. The resultant curves were compared with the adopted operational curves. The results of this comparison showed that the percentage difference was 4.0% and 7.7% for stage-storage capacity and stage-water surface area curves respectively.Mosul reservoir was surveyed to find out the reduction in its storage capacity and to develop new operational curves. The survey was performed over 12 days from May 15th to June 3rd, 2011 using to “Echo sounder sonar viewer type Sea Charter 480DF” linked to a “Real-Time Kinematic Global Positioning System (RTK-GPS)”. The bathymetric survey results indicated that the reduction in the storage capacity of the reservoir due to sediment deposition during the operating period was 1.143×109 m3. This represents 14.73% of the total storage capacity and the reduction in the live storage and dead storage was 11.8% and 19.62% respectively. Likewise, the survey suggested new operational curves for Mosul dam reservoir. The survey showed that most of the sedimentation was in the upper zone of the reservoir and gradually decreased towards the dam.

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  • 29.
    Huang, Yi
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Coarse dust particle transport model around Malmberget mining area2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The dust generated from mining activities in the mining area is an important environmental issue for modern mining industries with many environmental problems involved. Number of researcher worked on small dust particle transport, but few work related to the coarser dust particles with 10 to 100 micro meters diameters had been made despite the fact that coarser dust transport have significant influence on the human lives (e.g. dust deposit on the residential area nearby, and mining facilities which may bring commercial and safety problem to the people living close by and the mine operators). More complaints from the residents and the workers deserve such research work.The research on dust transport is aiming to track how dust transport and deposit around the mining area and its interrelationship with local climate and topographic conditions. The modeling work is based on some fluid sediment transport dynamic models, with 1D, 2D and 3D when the research steps go further on. The models illustrate the transport progress and the amount transported by the wind. A case study from Malmberget mine in northern Sweden has been made in 2010.The dust characteristic information was obtained from laboratory work in LTU, and local climate information was supplied by the SMHI (Swedish Meteorological and Hydrological Institute). Two transport models were developed and applied here: One is the computational model based upon the classical Bagnold’s (1941) equation; and the other one is the simulation model based upon the sedimentation engineering work from Al-Ansari (1976). The computational model calculates dust retention time for estimating the amount of dust transport in certain time period with provided wind and dust characteristic information. The simulation model used simple sediment transport model to simulate the dust grain movement in air flow, and conclude the transport amount of dust. Both models were enhanced by Matlab GUI to simplify the calculation procedure. The comparison of the results from the two models gave the similar variations and estimation of the transport amount for the given data. With more modification methods the models are expected to be more accurate. The application of the model is aiming to be enlarged to snow particles with changed criteria, 2D and 3D models would be designed in the future work to obtain the better results.

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  • 30.
    Andersson, Mattias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Kompressionsegenskaper hos sulfidjordar: En fält- och laboratoriestudie av provbankar2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this licentiate thesis is presented the work and the results of the construction of two testembankments on sulphide soils at the test field in Lampen outside the city of Kalix next to thenew rail road Haparandabanan.The main purpose of the licentiate thesis work was to improve the knowledge of compressionproperties of sulphide soils, with focus on the creep properties. Another aim was to establish atest field with extensive instrumented test embankments where settlements and pore pressurescan be measured during many decades.The work with the test embankments has included instrumentation and construction as well asmeasurements of deformations, pore water pressures and soil temperatures. Fieldinvestigations of the properties of the sulphide soil have been performed mainly by CPTsounding,field vane test and Swedish piston sampling. An extensive program of laboratorytests, mainly through oedometer tests, both incremental loading and constant rate of strain,permeability tests and undrained direct simple shear tests, was conducted for thedetermination of compression and strength properties. In this work a literature review wasperformed with the subject sulphide soils and focusing on compression properties. A firstsimple one-dimensional calculation of the total settlements of the test embankments wascarried out regarding the magnitude and the time dependency.The instrumentation and the construction of the test embankments have been carefullyplanned and were carried out as planned. The different measuring equipment as settlementhoses, bellow hoses, settlement gauges and inclinometers, which are installed in theembankments and the underlying sulphide soil to measure deformations in the soil, overallhas given the expected values and the behaviour can be explained by theories of soilmechanics. The pore pressure responses in the underlying sulphide soil are related to theapplied load caused by the mass of the embankments and the effective stresses in the soil. Theresults of the pore pressure measurements are comparable with previous experiences of thebehaviour of load testing on fine-grained soils.Many oedometer tests, incremental loading and constant rate of strain (CRS), have beenperformed to study the compression properties of the sulphide soil and to evaluate differentparameters. It has been possible to identify and evaluate the preconsolidation pressure fromall the CRS oedometer tests, which indicates a good quality of the soil samples, .i.e. a wellperformed piston sampling and following handling of the soil samples. In comparisonbetween the two different oedometer tests, incremental loading and constant rate of strain, thefirst one gave a slightly higher value of evaluated preconsolidation pressure.From the incremental loading tests the creep parameters, , and , were evaluated andthey indicate that the values of these parameters in the sulphide soil from Lampen are slightlyhigher than the previous experiences of sulphide soils have shown. This implies that it can berelatively large differences in creep properties between different sites with sulphide soils andthat incremental loading tests should be performed in the cases when creep settlements are ofinterestThe total calculated settlements of the two embankments in Lampen after 50 years arebetween 1.12 and 1.35 m, with the heights 1.5 m and 2.0 m respectively of the embankments The performed measurements of the settlements showed at the time for the latestmeasurements, i.e. 420 days after the start of the construction of the embankments, that thelargest measured settlements of the ground surface were between 0.34 and 0.38 m. Incomparison with the calculated results, these values were slightly higher, since thecalculations for the same time give settlements in the order of 0.26 to 0.30 m.In this work an extensive experimental basis for the future has been created for compressionproperties including creep properties of the investigated types of sulphide soils, withapplications to settlement calculations of embankments.

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  • 31.
    Al-Taie, Laith
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Performance of landfills of hazardous waste with special respect to the function of clay liners2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis is based on four papers related to the performance of near-surface low-level (LLW) repositories (landfills) focusing on construction and performance of clay liners in the cappings. The first paper discusses the source of hazardous wastes, their location and their impact on public health. The paper also discusses the scientific basis of the selection of the isolation of such wastes taking in account also cost issues. The paper also shows rules and principles of composing and constructing isolation of such waste according to American and German regulations. The second paper deals with the criteria for locating plants for processing and disposal of hazardous waste in Iraq with special respect to environmental, geological and socio-economic factors. Referring to these criteria a potential disposal site in the Al-Jezira desert is assessed in the paper. The third paper describes the properties of two candidate Iraqi smectitic clays of potential value for isolating hazardous wastes. These clays have been and are still being examined in order to determine their performance and usability for waste isolation. The fourth paper, finally, discusses in detail the hydration-dehydration processes in clay liners in cappings of waste landfills in desertic climates. It also deals with construction issues.

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  • 32.
    Zakaria, Saleh
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Rain water harvesting and supplemental irrigation at Sinjar district in northwest Iraq2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Rainwater harvesting is one of the methods that can ensure availability of water for winter crop in Iraq. Using this technique the excess rainwater (runoff) is stored in reservoirs of dams of different sizes. The water from these reservoirs can be used later when required to satisfy the crops requirements.It is believed that rainwater harvesting will be one of the solutions to overcome water shortages problem in Iraq.This work deals with rainwater harvesting modeling on Sinjar District. The area of study is a plan area located on the northern and southern flank of Sinjar Mountain, within Nineveh province in northwest Iraq. The model was first applied on southern of Sinjar Mountain, where barley crop was chosen as one of the main crops grown in the area. Linear programming technique was adopted to optimize the irrigated area for irrigation scenario of supplemental irrigation (SI) 100% of full irrigation requirements. Two scenarios of operation were considered for each main basin. In the first, each reservoir was operated as a separate unit while in the second all reservoirs in a basin were operated as one system. Both scenarios gave encouraging results. Scenario two however, was relatively better.And then the model was applied again on the northern Sinjar Mountain area. Wheat crop was considered as the main crop grown in the area. A linear programming technique was adopted to optimize the irrigated area for three scenarios of irrigation. They were: 1/supplemental irrigation (SI) 100%, 2/deficit irrigation (DI) 50%, 3/deficit irrigation (DI) 25% of full irrigation requirements. The results of the three scenarios used indicated that, using deficit irrigation (DI) of 50% can be more beneficial than SI of 100% and DI of 25% of full irrigation requirements. These results reflect useful value of RWH and its influence to increase the irrigated area in the studied region.This study had been carried out at Lulea University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Lulea, Sweden.The present work structured in seven chapters, and can be pursued as follows: In chapter 1, Background of the rainwater harvesting, aims of study and research methodology are addressed. In chapter 2, Scope of description of Water Resources in Iraq, Numbers and facts about Iraq, Present water resources conditions in Iraq, Irrigation practices in Iraq, Main Rivers of Iraq, Dams on Tigris and Euphrates Rivers, The impact of Southeastern Anatolia Project (GAP) on water resources in Iraq, Environmental Consequences and Groundwater in Iraq are described.In chapter 3, Information review on rainwater harvesting and supplemental irrigation is presented. In chapter 4, Description of the study area of the Sinjar District, simulation models used in the study and a research methodology are presented.In chapter 5, The results are presented and discussed for southern and northern of Sinjar Mountain. In chapter 6, Summaries for future study: water harvesting and groundwater recharge, water harvesting and its role in increasing crop productivity and the impact of forecasting on water harvesting. In chapter 7, Summaries for the overall conclusions based on the results and then references of the study are listed.Extended of thesis 1-Water harvesting and reservoir optimization of selected areas south Sinjar Mountain, Iraq, Lulea University of Technology, Sweden.Nadhir Al-Ansari, Mohammad Ezz-Aldeen, Sven Knutsson, Saleh Zakaria Submitted to the Journal of Hydrological Engineering. 2- Rainwater harvesting and supplemental irrigation at northern Sinjar Mountain, Iraq, Lulea University of Technology, Sweden.Saleh Zakaria, Nadhir Al-Ansari, Sven Knutsson, Mohammad Ezz-Aldeen Journal of Purity, Utility Reaction and Environment, Vol. 1 No.3,May 2012, 121-141.

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  • 33.
    Jia, Qi
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Dust from mining area and proposal of dust emission factors2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mining generates great deal of particulate matter, especially for surface mining. The principle of dust generation is based on the theory of soil wind erosion. This thesis theoretically and experimentally dealt with mining dust. In chapter 1 the development of study on soil erosion by wind and mining dust were introduced. Chapter 2 elaborated the process of soil wind erosion. Soil motion during wind erosion is classified into three categories which are creeping, saltation and suspension. Threshold wind velocity, which initiates particle motion, depends on particle size, soil moisture, roughness element etc. Roughness element refers to non erodible fraction in a soil. A test on erodible fraction was included in this research.Chapter 3 presented effects and sources of mining dust. Sources include haul road, stockpiles, open surfaces, overburden removal etc. Malmberget mine operated by LKAB is one of the most important iron mines in Sweden. The mining area includes an area with huge open pit and current industrial center area. Both areas are surrounded by residential areas where people are suffering from dust problem. In this research the collected dust from 26 measuring stations during the time period Aug. 2009 to Aug. 2010 were used to calculate the dust fallout and distribution using surfer 9.0 software. It was concluded that two sources for dust generation were spotted. One was located close to the open pit, and the other was located nearby the current mining industrial center. It should be mentioned that the concentration of dust was varying with time. The maximum value happened on May in 2010. The value suddenly became extremely high compared with the other months. This was attributed to a road construction at that time. Analysis results have shown dust production around Malmberget mine was attributed to three reasons: wind erosion of the exposed area closed to the open pit, trucks transportation on haul roads, and wind erosion of stockpiles. Since the mining activities were relatively going at a constant level, the variations of dust level were mostly attributed to the climatic factor. During the research erodible fractions for surface samples from the open surface nearby the open pit were measured. The result showed an erodibility index of 4.69kg/m2 per year. Because the index value indicated relatively low intrinsic soil erodibility, the dust problem might be more contributed by wind erosion of stockpiles and truck travelling on haul roads.Chapter 4 introduced how US EPA developed dust emission factors for various mining activities. Accordingly recommendations and the future plans for the establishment of the dust emission factors for Malmberget mine in Sweden were given and highlighted in chapter 5. Chapter 6 finalizes the thesis with a conclusive paragraph.

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  • 34.
    Bernander, Stig
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Progressive landslides in long natural slopes: Formation, potential extension and configuration of finished slides in strain-softening soils2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    After the large landslide in Tuve (Gothenburg, 1977), the author began developing a finite difference model for slope stability analysis taking the deformation-softening of soft sensitive clays into consideration. In the model, the mean down-slope deformation in each element caused by normal forces is maintained compatible with the deformation generated by shear stresses. He developed software for the model and presented it at international soil mechanics conferences during the 1980-ies. In 2000 he summarized his findings in a Licentiate thesis. An easy-to-use spread-sheet has also been developed. In this thesis the author conveys his experiences of slide modeling focusing on the nature of triggering agents and the different phases that a slope may undergo before its stability becomes truly critical.

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  • 35.
    Zardari, Muhammad Auchar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stability of tailings dams: focus on numerical modelling2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Upstream tailings dams may experience slope stability problems when the rate of raising is too fast. Tailings consolidate slowly due to low hydraulic conductivity. The excess pore pressures can build up due to accelerated rate of raising. The cumulative increase in excess pore pressures due to successive raisings can endanger slope stability of a tailings dam. The stability of a tailings dam is closely related to the consolidation process. The consolidation process and associated stability of an upstream tailings dam during staged construction was modelled with the finite element program PLAXIS. The analysis indicated that the stability of the dam reduced during raising due to increase of excess pore pressures. The safety of the dam was improved by adding rockfill banks on the downstream side. The volume of the rockfill banks was minimized with an optimization technique. This technique involves (i) construction of a rockfill bank on the downstream side when the factor of safety is less than a permissible limit, (ii) utilization of a minimum volume of the rockfill that is necessary to stabilize the slope. This technique can be practicable when the rate of raising is moderate, and partial consolidation occurs between consecutive raisings. Numerical analysis was also performed on a curved embankment of an upstream tailings dam in order to investigate the possible risk of hydraulic fracturing and internal erosion in a corner of the dam. The analysis showed that low compressive stresses occurred above the phreatic level, near the zones of filter and rockfill banks. These zones contain coarse material, and are, therefore, not susceptible to hydraulic fracturing and internal erosion. An increase in the radius of the corner is suggested in order to prevent large reductions in compressive stresses that may occur due to future raisings. Presently the curved dam section is stable. However, an additional rockfill bank on the downstream side will be required for future raisings. Static liquefaction is considered as a common cause of disastrous flow failures of tailings dams. These flow failures can be predicted with numerical modelling using suitable constitutive models. In this context, some constitutive models capable of simulating static liquefaction behaviour of loose saturated sands are reviewed. It is generally concluded that the finite element method can be a helpful tool for modelling stability of tailings dams.

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  • 36.
    Berglund, Andreas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Prognos av vägars bärförmåga vid tjällossningen: användning av temperatur som nyckeltal2010Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The global trend towards a warmer climate and temperatures near or just above 0 °C during winter months, will most likely be more common in future. One of the consequences of this climate change could, in a worst-case scenario, be freezing and thawing over a significant part of the winter with corresponding road bearing capacity problems. Bearing capacity problems may lead to increased costs to society when heavy traffic is forced to change route or carry less weight. In addition, road maintenance costs will increase. According to pulp industry calculations, this industry sector will face additional costs in the range of 510-590 Million SEK every year due to road bearing capacity problems. In addition to this, the costs related to the rapidly growing bio fuel industry will be added. If a reliable forecast of load-bearing capacity problems and potential load restrictions on roads can be found, it would be cost effective for road administration and society. This text presents the content of the licentiate work is presented and in what report more information could be found. One aspect of frost damage on roads that is highlighted in the thesis is decision making when conducting a road inventory. In a study conducted within the licentiate work it was shown that the results from different actors performing frost inventory on the same road stretch can vary a lot. There should be efforts made to reduce the individual dependence when performing a road inventory. The main part of the licentiate work deals with a model for the prediction of bearing capacity problems on roads. The work gives an idea of the possibility to use the temperature based model used in Minnesota, USA in Sweden. The evaluation is done by comparing falling weight deflectometer (FWD) test results with the results from the temperature based forecast model. When comparing the FWD results: AREA-parameter and subgrade modulus with results from the Minnesota model, the subgrade modulus seems to have the greatest agreement with the forecast model. However, they both seem to show the overall development of low bearing capacity during thaw. The overall conclusion about the temperature based forecast model is that it seems to give fairly good results and work well. It will work better if it can be further calibrated but it has some flaws if the temperature seesaws around 0 °C. The forecast model should, despite this, be able to assist road holders in Sweden as a planning tool, when dealing with bearing capacity problems during thaw.

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  • 37.
    Jantzer, Isabel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Critical hydraulic gradients in tailings dams: comparison to natural analogies2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing demand of metals and minerals has made it economical for the mining industry to mine low-grade deposits, which results in immense quantities of by-products. In fact, such by-products, i.e. tailings, are the largest waste volumes produced on earth. Ore from sulfide rich geological formations result in sulfide rich tailings that can cause major environmental problems upon oxidation and acidic seepage. One way of economically and effectively preventing unwanted chemical reactions and leaching is the deposition in an impoundment surrounded by tailings dams, where tailings are allowed to settle and covered effectively by a water level against oxidation.In order to prevent environmental impacts and possible long term contamination from tailings dams, the Swedish Environmental Protection Agency (Naturvårdsverket), demands a long term stability without maintenance that refers to thousands of years or more, resulting in a design period of 1000 years for tailings dams. The stability of tailings dams in long term perspective depends, amongst others, on the prevention of internal erosion, a process that results from an exceeding seepage pressure causing particles in a dam to migrate, with possible consequences of damage and failure of the dam construction. Therefore, the main question in this thesis is: Which maximum hydraulic gradient can we allow for a tailings dam construction in order to prevent internal erosion in a long term perspective?With regard to the long term design of tailings dams, natural analogies to dam constructions are considered, i.e. formations from the last glaciation period that have fulfilled the task of damming water. Such structures are especially interesting with regard to their obvious stability against internal erosion over long time, otherwise they did not exist today. Consequently, it is assumed that a critical hydraulic gradient exists, and that the material composition and compaction reaches an optimum which allows seepage without erosion. This study provides basic knowledge on tailings dam construction and a State-of-the-Art report on current knowledge on internal erosion. A summary of natural analogies to dam constructions that have been stable dams since the last glaciation in Sweden is presented. In the context of this work, a case study was conducted at the company area of Boliden in Gällivare, northern Sweden, with the aim to study the geotechnical properties of such a natural stable embankment. This case study includes field studies, ground water monitoring and sampling. Complementing laboratory analysis covers an analysis of the materials' properties with regard to composition, density, compaction and hydraulic conductivity. The formation consist of a well graded glacial till which is compacted to an optimum in situ above what could be obtained in laboratory conditions. The hydraulic conductivity of laboratory compacted samples shows a minimum of 2,60 * 10-10, which implies that the material is practically impermeable, which may be an explanation for the absence of ground water during monitoring.Critical hydraulic gradients found in literature range between 4,8 and 14 %. Current tailings dam design guidelines in Sweden relate the maximum gradient to the internal angle of friction, thus resulting in gradients of about 12 to 27 %. Gradients in long term stable natural formations are between 2 to 5 %. The calculated hydraulic gradient in the case study is 6,7 %; however, the actual gradient could not be determined due to the absence of pore pressure measurements during ground water monitoring. With regard to long term stability, possible degradation and results from comparisons to long term stable natural analogies, a modification of the design criteria for Swedish tailings dams should be considered.

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  • 38.
    Johansson, Eva
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Free mica in crushed rock aggregates2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Free mica particles in crushed rock aggregates for constructional purposes affect the quality of the end product. It is also known that mica-bearing rocks may cause damages of the road constructions, especially in regions with a temperate climate. The negative influence arises in both bounded and unbounded layers. The deterioration of the construction is related to the ability of mica particles to be released during crushing and to concentrate in the aggregate fine fractions. As the free mica particles absorb and hold liquid such as bitumen and water, the unbounded base course becomes susceptible to frost weathering and the mechanical properties of the asphalt mixture are negatively influenced. The water absorption ability is in turn caused by an increased specific surface area of the fine fraction depending on the grain shape of mica particles and their intra crystalline cavities. The aim of the present study was to investigate, emphasise, and contribute to an understanding of the performance of free mica particles in the fine fractions of crushed rock aggregates. The free mica problems are well- known, but sparsely taken into account in projecting and prospecting activities. The mineralogical composition (i.e. the quality) of the rock material is often a subordinated task in early stages in planning for roads and railways. Connected with establishment of quarries the estimation of rock materials quality is generally based on petrographic and mechanical analyses of drill-cores.The study presented consists of: * The investigation of the ability of free mica particles to enrich in fine fractions of granitoid crushed rock aggregates. The comparison study to examine a possible correlation between the content of mica in original rock materials, the content of free mica particles in rock aggregate products, and the content of free mica particles in drill cuttings. * The development of a method to estimate free mica particles in aggregate fine fractions using image analysis of grain mounts. * The development and practical applicability of a method to estimate rock aggregates quality using analyses of drill cuttings. The study reveals that mica-bearing rocks exposed to mechanical impact release free mica particles that concentrate in the fine fractions of crushed rock aggregates. The original grain size of mica in the host rock is suggested to influence on the process. Coarse-grained rocks seem to separate free mica grains in earlier phases of the crushing process than fine-grained ones. The enrichment is suggested to depend on the textural characteristics of the rock rather than on the mineralogical composition. These aspects must be taken into consideration when the grain size fractions for analyses of free mica content are selected. The statistical evaluation of the new method for estimation of free mica particles points out its certainty and repeatability. Due to the possibility to save the images of the statistical operation, the results of the method are controllable. These factors mentioned make the method satisfactory and statistically acceptable from a scientific point of view. The concept using drill cuttings for estimation of rock aggregates quality is practically tested and evaluated as an effective field method. The further development and calibration should focus on improvement of sampling concerning the content of coarse drill cuttings. The homogeneity/heterogeneity of the bedrock is crucial for the selection of the samples and stresses the necessity of representative sampling.

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  • 39.
    Eitzenberger, Andreas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Inventory of geomechanical phenomena related to train-induced vibrations from tunnels2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Banverket is expecting that the number of railway tunnels in densely populated areas will increase over the next 20 years due to the lack of available space on the ground surface, but also since the railway is considered an environmentally friendly solution of transportation for the future. The need for good predictions of vibration and noise levels in dwellings along the planned tunnels is therefore evident. Due to lack of understanding of the propagation of train-induced vibrations from tunnels in rock a research project has been initiated by Banverket. This thesis constitutes the first stage of that project. In this thesis, the propagation of vibrations through a rock mass has been reviewed. The emphasis has been on wave propagation in hard rock masses. Areas, such as the generation of vibrations at the train-rail interface, the response of buildings and humans, national and international recommended noise and vibrations levels, and possible countermeasures are briefly reviewed as well. Finally, suggestions for the continued research are presented. The propagation of waves is influenced by attenuation along the propagation path. The attenuation can either be through geometric spreading, energy loss within the material, or reflection and refraction at boundaries. In a rock mass, where heterogeneities of various scales are present, the attenuation of (train-induced) waves through the ground therefore mainly depends on the properties of the discontinuities. Theoretical models of wave propagation across individual fractures have been presented in the literature. These models can be used to study the attenuation at the fracture for different combinations of joint stiffness, impedance, and angle of incidence. Also multiple parallel joints can be theoretically analysed. The attenuation of low-frequency waves is more prominent in weak rock masses and virtually negligible for hard rock masses. An increased amount of random oriented joints, faults and boundaries increases the attenuation of the waves, but is not possible to study with the aid of theoretical models. The rock mass is in most cases inhomogeneous due to all heterogeneities present. Despite this fact, the rock mass and soil is always treated as an isotropic, homogeneous material in the analyses of ground-borne noise and ground-borne vibrations. This concerns both numerical and empirical methods. Thus, there is a lack of a method that considers the influence of various heterogeneities present in a rock mass on the propagation of waves. Future research regarding train-induced vibrations should focus on combining the models of attenuation in the material with the models of attenuation across joints. Thereafter, conceptual models should be used to determine the propagation of low-frequency waves in a rock mass containing various amounts of heterogeneities (from isotropic to highly inhomogeneous) which should be compared to the theoretical methods available. Once the behaviour of waves in an inhomogeneous rock mass has been established, conceptual models should be used together with measurements from a few well documented cases. From the results of the analysis, guidelines for analysis of railway tunnels with regard to ground-borne noise and ground-borne vibrations should be established.

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  • 40. Kondelchuk, Dimitri
    Studies of the free mica properties and its influence on quality of road constructions2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis presents series of laboratory studies of aggregates containing mica minerals obtained from aggregate producers located throughout Sweden. The main idea of the research was to study physical properties and behaviour of free mica particles in unbound granular products of crushed rock materials. Another objective was to highlight the detrimental properties of mica occurrence in aggregates used for road construction industry and determine the applicable methods for quantitative determination of mica minerals presence. Due to the lack of previous investigations looking at this or similar subject, the current research can have international importance, especially for countries with crystalline, mica rich bedrock and temperate, subarctic climates. Recently a number of cases involving road construction failures and decrease in service life have been observed in northern parts of Sweden. One of the major reasons for the structural deterioration was enrichment of free mica particles in aggregates and their interaction with water. Due to this reason first paper of this thesis represents a study of the behaviour of free mica grains in crushed rock aggregates of metamorphic origin and recognition of any trend of enrichment of free mica grains aggregates. As a result two general trends of enrichment of mica were obtained: Type I (isotropic source rock) and Type A (anisotropic source rock). Type I is exemplified by a general increase of free mica towards finer grain fractions, with or without a peak for "coarser" grain fractions. Type A represents an increase of free mica up to a certain grain fraction, thereafter no increase occurs towards finer grain fractions. Second part of the thesis focuses on the determination of the possible analytical methods which are susceptible to mica content and could be used as indicating technique for quantitative determination of free mica particles in unbound granular materials. Two standard methods: Sand equivalent test and Methylene blue test were assumed as the most sensitive to mica presence. Both methods showed susceptibility to mica content and gave strong correlation in terms of mica content. The third paper enhances knowledge of the behaviour of mica rich aggregates in interaction with water in terms of fraction sizes and free mica content. During the experiment several aggregates with different content of free mica and pure mica material consisting of commercial biotite were studied. Two major parameters were investigated during the research: water storage capacity and specific water saturation value. With the aid of consecutive analytical and statistical analyses a more precise mica presence threshold value for certain unbound applications was indicated, resulting in recommendations for industry, authorities and for future experiments.

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  • 41.
    Novikov, Evgeny
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    The behaviour of mica-rich aggregates under the temperate climate conditions2008Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In regions of temperate climate the destructive influence of frost action such as frost heave in winter and thaw weakening in spring are the main contributors to severe deterioration of the pavement structure. A number of studies on construction aggregates and field observations of road failures, especially caused by seasonal fluctuations of temperature, have revealed a negative influence of unbound mica-rich rock aggregates on the service life of road construction. The aim of this thesis was to investigate the behaviour of mica-rich aggregates under the temperate climate conditions. The study focuses on measurements of volume change (frost heave), capillarity rise and interaction between water and mica-rich aggregates. The materials studied in this research are commercially available unbound road construction aggregates with varying free mica grains, and originating from different regions of Sweden. The mineral composition of the samples has been determined by polarizing microscopy using a point-count method. In Paper I, the materials were exposed to freeze-thaw cycling in order to register the volume change (in terms of frost heave). The results show that mica-rich base-course aggregates have a large potential to produce frost heave. The results from the test for determining capillary rise (Paper II) indicate a direct correlation between mica content of the aggregates and capillary rise values confirming the capability of mica-rich unbound aggregates to transport and absorb higher amounts of water. The interaction of mica-rich aggregates with water in terms fraction sizes and free mica content was studied in Paper III, measuring water storage capacity and specific water saturation values. The results reveal a strong positive correlation between mica content, grain size, water sorption and water storage capacity of the aggregates. The overall results of this research bring the mineralogy of the fines into focus when evaluating frost susceptibility of unbound aggregates and can be considered when estimating threshold values of free mica grains in crushed road materials.

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  • 42.
    Hellström, J. Gunnar I.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fluid mechanics of internal erosion in embankment dams2007In: Parallel computing of fluid flow through porous media, Luleå: Luleå tekniska universitet, 2007Chapter in book (Other academic)
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  • 43.
    Åkerlund, Håkan
    Luleå University of Technology.
    Dränerande sildammar för deponering av anrikningssand2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [sv]

    Vid gruvbrytning genereras bland annat ett finmalet gråbergsavfall, anrikningssand. Den vanligaste deponeringsmetoden för anrikningssand är att den tillsammans med vatten pumpas eller leds till en gruvdamm. Där deponeras anrikningssanden genom sedimentation. Trots att det är den vanligaste deponeringsmetoden är den behäftad med svagheter. Det uppdämda vattnet i gruvdammen kan ge upphov till incidenter och i olyckliga fall till allvarliga haverier. Ett sätt att minska riskerna och att öka stabiliteten, är att deponeringen sker under dränerade förhållanden. Detta kan åstadkommas med hjälp av sildammar. För att studera funktion och lämplig uppbyggnad av sildammar har ett anta fält- och laboratorieförsök genomförts. Grovkornigt gråbergsavfall, kallat sovringsgråberg, användes när sildammarna byggdes. Sildammarnas uppgift var att hindra flödet av anrikningssand genom filtrering och samtidigt tillåta dränering av inpumpat vatten. Syftet med denna licentiatuppsats har varit att hitta en lämplig design för sildammar. Efter en inledande litteraturstudie byggdes testanläggningar, både som rännförsök och i pilotskala. I testanläggningarna testades olika sildammar genom att dess filtrerande och dränerande förmåga undersöktes. Testerna föregicks av laboratorieförsök där sildammsmaterialens hydrauliska konduktivitet undersöktes. Testerna visar att vid valet av lämpligt material för sildammar, kan filterkriteria användas tillsammans med bedömningar av materialets hydrauliska konduktivitet. Finns inte lämpligt sovringsgråberg att tillgå, kan geotextiler användas som filter i en sildamm. Sildammarnas filtrerande förmåga beräknades som verkningsgrader, vilka låg mellan 34 - 100 % beroende på sildammarnas design. Sildammarnas dränerande förmåga beräknades i det deponerade materialet med hjälp av uppmätta och beräknade porvattentryck. Porvattentrycken sjönk mellan 60 - 100 % under testperioden. Testerna visar att det deponerade materialets egenskaper påverkas av den inpumpade mängden av vatten och anrikningssand samt av sildammarnas funktion. Där sildammens filtrerande förmåga var hög, tog det längre tid innan det deponerade materialet dränerades. Vidare påverkas sildammarnas funktion av det deponerade materialets egenskaper. Vid deponeringen skedde en partikelsegregering, då de tyngsta partiklarna sedimenterade närmast inloppsröret medan lättare partiklar transporterades längre innan de sedimenterade. Denna segregation påverkar sildammens dränerande funktion negativt. Sildammen kan inte filtrera enbart de finkornigaste partiklarna samtidigt som sildammen skall dränera det inpumpade vattnet. Ju mer omfattande partikelsegregationen är och ju bättre sildammen kan hindra de finkornigaste partiklarna, desto större kommer sättningarna i det sedimenterade materialet bli nära sildammen. Detta kan försvåra dränering av ytvattnet. Testerna genomfördes sommartid. Framtida undersökningar bör koncentreras på att anpassa metoden även för vinterförhållanden. Vidare bör materialprover tas för att få en bättre uppskattning av partikelsegregationen. Målet är att kunna beräkna deponins optimala storlek. Slutligen bör ytterligare fältförsök genomföras där anrikningssanden deponeras i våningar. Vid dessa försök bör det deponerade materialets dräneringsförmåga ytterligare utredas tillsammans med undersökningar av eventuella erosionsproblem i underliggande sildammar från dränerat vattnet.

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  • 44.
    Johansson, Karin
    Luleå University of Technology.
    Planeringshjälpmedel för ökad tillgänglighet på grusvägnätet: en studie av datorverktyget HDM-42005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    I dagsläget saknas i Sverige ett verktyg som behandlar både belagda och icke-belagda vägar i arbetet med långtidsplanering av vägnätet. För att kunna göra en riktig fördelning av resurser för drift- och underhållsåtgärder över vägnätet krävs ett verktyg som kan behandla samtliga vägtyper och som ger jämförbara resultat. Genom att använda programmet "Highway Development and Management systems", HDM-4, är det möjligt att simulera nedbrytning och åtgärdseffekter för det totala vägnätet, som en enhet. Målet med detta är att kunna simulera vägars tillståndsutveckling och lönsamhet vid olika underhållsstrategier, oavsett beläggningstyp. Kan detta uppnås är förhoppningen att man utifrån en begränsad budget kan utföra det lämpligaste underhållet för att öka standarden på vägnätet. Det faktum att grusvägsmodulen i HDM-4 inte nyttjas i områden med kallt klimat, samt att nedbrytnings- och åtgärdsmodellerna är utvecklade utifrån studier gjorda i områden med totalt annat klimat än Sverige gör att dessa bör valideras innan programmet tas i bruk. Syftet med detta arbete är att genom simuleringar av tillståndsutvecklingen för ett antal grusvägar visa på brister, användningsområden och möjliga idéer till förbättringar av HDM-4. Studier av nedbrytnings- och åtgärdsmodellerna visar på brister i främst anpassningen av modellerna till vinterklimat. I simuleringar med HDM-4 antas ojämnhetsutveckling och materialförlusten från en grusväg vara lika stor över hela året. Detta kan vara rimligt i områden där vägarna inte är snötäckta och frusna stora delar av året. Detta är dock fallet i norra Sverige. Det faktum att nedbrytningen av en väg inte sker på samma sätt under vinterhalvåret som under barmarksperioden tas det heller ingen hänsyn till i modellerna. Simuleringarna visar på möjligheter att använda HDM-4 för att se trender i ojämnhetsutveckling och materialtransport för olika åtgärdsstrategier. De faktorer i modellerna som tar hänsyn till klimat går inte enkelt att anpassa till nordiska förhållanden. Detta medför att tillförlitligheten av de numeriska värdena från simuleringarna bör behandlas med försiktighet när programmet används. Försök med att endast simulera barmarksperioden har även utförts. Dessa visar på en möjlig lösning till att enbart simulera nedbrytningen och effekterna av åtgärder under barmarksperioden. Utifrån de studier av programmet som hittills har utförts finns en möjlighet att kunna använda programmet för prioritering av insatser för det svenska grusvägnätet på en översiktlig nivå. Detta utan att ändra i de ekvationer som ligger till grund för nedbrytningsmodellerna. Programmet är däremot för grovt för att använda vid studier av enstaka objekt i detalj. De variationer i IRI som återspeglar olika nivåer av åtgärder kan tydligt identifieras, vilket innebär att programmet kan användas för att urskilja trender i ojämnhetsutvecklingen för olika åtgärdsalternativ. Ytterligare studier bör utföras för att testa de idéer till ändringar som hittills kommit fram i projektet.

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  • 45.
    Bjelkevik, Annika
    Luleå University of Technology.
    Stability of tailings dams: focus on water cover closure2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mining activities have been ongoing for thousands of years within Sweden. As the results of previous activities are evident today, i.e. for example acid mine drainage (AMD), the focus and interest on closure and remediation of mine sites and tailings storage facilities (TSFs) has increased. At present all mines in operation have closure plans according to legal requirements. The purpose of a closure plan is to make sure that the site is safe when the mine comes to an end and the mining company abandons the site. The need for remediation of TSFs, where the fine (crushed and milled) waste material, i.e. tailings, from the process plant is stored, is important with regard to the consequences for the future environment. The composition of the tailings vary, i.e. content of chemicals, minerals etc., from mine site to mine site. Unwanted processes taking place in the tailings within the TSF may result in acidic leachate and leaching of metals and heavy metals from the TSF. These processes will be harmful for the environment and must therefore be prevented or reduced to levels that the environment can handle. They need to be controlled through a proper remediation and closure design of the facility. One method to control these processes is by covering the impoundment with water. One of the most important requirements when using this method is the stability of the tailings dams surrounding the impoundment. Without stable tailing dams the water cover will not stay. Long term stability of tailings dams has been the focus of this research project. Long term has in this case been set to 1000 years or more, which has become an international praxis in the last couple of years. To understand what we need to know in order to achieve long term stable tailings dams several areas have been studied. One idea used, was that we need to know, and understand, how tailings dams in operation perform today in order to understand how they may perform in a long term perspective. This resulted in studies of tailings dam safety in Sweden (see Benckert , 2003 and 2004) and of incidents and failures at Swedish tailings dams (see Bjelkevik, 2005b and 2005c). Another field of importance is the properties of tailings and for dam stability purposes the mechanical properties of tailings as a construction material. Sampling and laboratory tests where performed in 2002/2003 in order to compare the properties of tailings with natural materials (see Bjelkevik and Knutsson, 2005a). The conclusion drawn is that tailings have different properties compared to natural materials and the way of testing tailings material need to be calibrated for these differences. It was also concluded that this is a field requiring much more attention in the future. The focus of this thesis has been the long term dam stability and the factors and processes affecting this. In the State of the Art report (Bjelkevik, 2005d) this is covered and discussed. The most important factors for long term dam stability are: the hydraulic gradient and its relation to internal erosion extreme events like floods, drought, high winds, earthquakes etc. slow deterioration processes like erosion, weathering, frost and ice forces etc. These aspects have been analysed and discussed within the thesis. One valuable source for improving our knowledge on long term stability is natural analogies that have been stable since the last glacial period. Another valuable source is ancient structures, like man made earthen mounds and dams. Existing knowledge of some of these types of structures are presented in the thesis. The author, however, believes that there are a lot more information and knowledge to gain from analysis of these types of structures. Finally, the conclusions from this research project are: no Swedish tailings dams can be regarded as long term stable today it is possible to design long term stable tailings dams more knowledge can be gained from natural analogies and ancient structures the most challenging aspects in designing long term stable tailings dams are probably not the technical aspects, but the non-technical In order to be able to define criteria for long term stable tailings dams several areas need further attention and research. Examples of these areas are: internal erosion long term changes in material properties the effect of the hydraulic gradient on slope stability interaction between tailings material and sealing elements/foundation within the tailings dam external erosion seepage points

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  • 46.
    Rostmark, Susanne
    Luleå University of Technology.
    Frysmuddringsteknik för sanering av förorenade sedimentområden2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Ett sediment är jordmaterial som ackumulerats på botten av sjöar, hav eller vattendrag i lös och okonsoliderad form. Antropogen påverkan i form av utsläpp från industrier och avlopp har under det senaste decenniet förorenat sedimenten. Utsläppen har skett dels som kontinuerliga mindre utsläpp men också som större mer katastroflika incidenter. Större medvetenhet och en skarpare lagstiftning har minskat utsläppen, men problemet med redan förorenade områden kvarstår. För att ta itu med frågan har en rad olika saneringsmetoder utvecklats, metoderna kan delas upp i; in situ metoder och metoder där sedimentet avlägsnas. In situ metoder omfattar olika typer av övertäckning och metoder som bryter ner föroreningen på plats. De tekniker som avlägsnar sedimentet är dränering följt av grävning eller muddring. Tekniskt sett är muddring omflyttning av sediment. Muddring kan delas in i mekanisk- och hydrauliskmuddring. Benämningen miljömuddring används för metoder som anses kunna utföras med liten risk för förorening under upptaget och god precision i hur mycket sediment som tas upp. Fördelen med att använda muddring som saneringsalternativ för förorenade sediment är att man avlägsnar de förorenade materialet permanent. Det finns idag en hel rad med kommersiellt tillgängliga muddringsutrustningar som lämpar sig både för olika djup och hårda eller lösa sediment. Själva muddringen har en relativt låg kostnad och går snabbt. Avvattning, behandling och deponering av muddrade sediment ökar kostnaden avsevärt och det finns en risk för exponering av människor under själva arbetets gång. En annan risk med muddring är att det under upptaget sker en resuspension av det förorenade sedimentet, den kan orsaka hög turbiditet, spridning av föroreningar och problem med återkontamination av den muddrade ytan. Turbiditet orsakar störningar i det bentiska och akvatiska habitatet och ger på kort sikt en ökad biotillgänglighet av föroreningen. Stenblock och andra störande föremål försämrar effektiviteten vid muddring. För att tackla problemen med upptag av sediment har Luleå tekniska universitet och FriGeo AB utvecklat en teknik som kan benämnas frysmuddring. Frysmuddring är en tillämpning av artificiell markfrysning. Syftet är att med frysning stabilisera det förorenade sedimentet in situ för att sedan lyfta det i frusen form. Fördelen med frysmuddring är att den orsakar mycket liten spridning av förorenat material samtidigt som det inte sker någon extra inblandning av vatten. Frysningen ger upphov till en aggregering av de fasta partiklarna, aggregeringen kan ha en positiv effekt på möjligheten att avvattna materialet. Frysningen utförs genom att en köldbärarvätska cirkuleras i enheter som kallas frysceller, en fryscell kan bestå av en grupp rör som sticks ned i sedimentet eller av en platta som läggs ovanpå. När materialet har frusit, lyfts det upp och lastas av, sedan omplaceras fryscellen och proceduren upprepas. För att utföra en frysmuddring behövs en kylanläggning och en lyftenhet. Artificiell markfrysning är ingen nyhet i sig, metoden användes i södra Wales redan 1862 och patenterades i Tyskland 1883. Sedan dess har tekniken använts för många temporära och permanenta applikationer. Mest används markfrysning för stabilisering vid olika typer av byggnadsarbeten och lining av underjordiska gastankar. I de arktiska regionerna använder man artificiell frysning för att bibehålla permafrost under uppvärmda byggnader och vid pipelines. Då en jordprofil fryser sker en rad interaktioner mellan vatten, fasta partiklar och luft. Om profilen innehåller föroreningar blir processen än mer komplicerad. Det finns ett ökande intresse för att utveckla frysning för miljörelaterade tillämpningar. Ett exempel är inkapsling av radioaktiva material och ett annat att använda frysa/tina cykeln för att rena förorenad mark. För att kunna utvärdera användningen av de nya teknikerna krävs kunskaper kring de geokemiska effekterna av frysning. Design av system för frysning och upptag av sediment förutsätter att man kan förutsäga frysfrontens utbredning. Den valda frystemperaturen har en avgörande betydelse för förloppet men det är även att ha god kännedom om de olika sedimentmaterialens värmetekniska egenskaper. Materialegenskaperna avgör frysfrontens läge som funktion av tiden. Frysmuddring kan användas för andra ändamål än upptag av förorenade sediment, tekniken är också ett intressant alternativ för bärgning av miljöstörande föremål eller ammunition. Frysmuddring kan också användas för upptag av sediment i arkeologiskt eller kriminaltekniskt intressanta områden.

  • 47.
    Edeskär, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gummiklipp som konstruktionsmaterial i mark- och anläggningstekniska tillämpningar2004Licentiate thesis, monograph (Other academic)
    Abstract [sv]

    I och med EG:s avfallsdirektiv från 1999 är det förbjudet att deponera hela däck från och med 2003 och förbjudet att deponera fragmenterade däck (gummiklipp) från och med 2006. Lagstiftningen syftar till ökad återanvändning eller återvinning av uttjänta däck. I Nordamerika, där liknande lagstiftning finns, har hela och fragmenterade däck använts i 30 år i vägbyggnadssammanhang som bland annat tjälisolerings- och lättfyllnadsmaterial. Syftet med detta licentiatarbete är att samla ihop och värdera den idag tillgängliga kunskapen om gummiklipps tekniska och miljömässiga egenskaper samt skaffa praktisk erfarenhet av att använda materialet i mark- och anläggningstekniska tillämpningar. Med gummiklipp avses fragmenterade däck där de enskilda bitarna varierar från ca. 30×30 mm2 till ca. 100×300 mm2. De övergripande målen med detta licentiatarbete är att: a) Identifiera, analysera och presentera den idag tillgängliga kunskapen om gummiklipps tekniska och miljömässiga egenskaper kopplat till mark- och anläggningstekniska tillämpningar. b) Genom egna fält- och laboratorieförsök skaffa praktisk erfarenhet av att använda materialet i vägkonstruktioner. c) Ge rekommendationer angående användande av materialet i mark- och anläggningstekniska tillämpningar. En vägsträcka med gummiklipp som skyddslager har byggts och utvärderats. Utrustning har installerats i vägkonstruktionerna för mätning av temperaturer, tjälfronten, sättningar och lakvatten. Konstruktionernas styvhet har bestämts genom fallviktsmätning. Tekniska egenskaper och erhållet lakvatten har jämförts mellan provsträckor och referenssträckan. Syftet med byggandet av provsträckan med gummiklipp som skyddslager är att: a) Erhålla kunskaper om att bygga med materialet. b) Studera funktionen av materialet ur tjälisoleringssynpunkt. c) Studera hur överbyggnaden ska dimensioneras för att kompensera för elasticiteten och styvheten i materialet. Målet med teststräckan är att kunna genomföra mätningar och utvärdering av sättningar av gummiklippslagret, temperaturer och tjälgränsen i vägkonstruktionen, konstruktionens styvhet (bärförmåga) och lakvatten från konstruktionen. Litteraturstudien visar att de karakteristiska egenskaperna för gummiklipp, i jämförelse med friktionsjord, är att materialet är lätt (låg densitet), elastiskt, dränerande och värmeisolerande. Gummiklipp är ett relativt kompressibelt material och många tekniska egenskaper beror av aktuell belastning. Materialet blir styvare med ökad belastning. De ämnesgrupper hos gummiklipp som främst är undersökta ur miljösynpunkt är metaller, PAH och i viss mån fenoler. I en anläggningsteknisk tillämpning är det normalt vattenburna föroreningar som är av intresse för vilken miljöpåverkan materialet kan ha på omgivningen. Lakförsök visar att metaller lakar ut från däcklipp, främst järn, koppar, mangan och zink. Metalläckaget är av samma storleksordning som för bergmaterial. Av studerade organiska föreningar lakar PAH och fenoler ut, i låga koncentrationer. Toxikologiska studier visar att lakvatten från däckmaterial har påvisbar negativ effekt på organismer. Färskt däckmaterial uppvisar större negativ respons på organismer än äldre material. Vägen med gummiklipp i skyddslager byggdes under perioden 2002-2003. Dimensioneringsarbetet med provsträckan visade att den uppskattade livslängden på konstruktionen inte påverkades nämnvärt av att styvhetsmodulen för skyddslagret varierades inom intervallet 0,25-2,0 MPa. Gummiklipp kan hanteras med konventionell utrustning som används vid vägbyggande. I vissa avseenden är gummiklipp mer lätthanterligt än konventionella vägbyggnadsmaterial som bergkross och friktionsjord, exempelvis håller materialet ihop bättre. Utvärderingen av vägkonstruktionen fram till färdigställandet av vägen visade att: a) Den utvärderade bärförmågan hos gummiklippslagret var lägre än förväntat. b) Den primära kompressionen av gummiklippet skilde mycket i storlek mellan de två delsträckorna med olika material i förstärkningslagret. c) Gummiklipp har en tjälisolerande förmåga. d) Gummiklippen lakar ut små mängder metaller och PAH. PAH-halterna var något högre än förväntat. Den färdigställda vägkonstruktionen kommer framledes att utvärderas fortlöpande dels för att jämföra dimensioneringsresultaten med verkliga konstruktionens egenskaper avseende bärförmåga och livslängd, och dels för att följa upp deformationer och tjälisoleringsförmåga samt bestämma lakvattnets sammansättning. Utifrån kunskapsnivån avseende de tekniska parametrarna som redovisats i denna avhandling kan tillämpningar pekas ut där kunskapsläget är tillräckligt för att rent tekniskt kunna använda materialet och tillämpningar där forskningsbehovet är större. Tillämpningar där tillräcklig kunskap avseende tekniska egenskaper idag kan anses finnas är bankfyllningar, dräneringslager, tjälisolering och motfyllnad. De tekniska begränsningarna som idag finns när det gäller användning av gummiklipp rör främst de elastiska egenskaperna i materialet, främst avseende styvhet och kompressibilitet. Miljöaspekten måste beaktas vid användning av gummiklipp. Vid känsliga recipienter och där avrinningsvatten kan ansamlas i små volymer kan materialet i extremfallet innebära en negativ påverkan. Placerat i applikationer där perkolationen är liten och kontakttiden mellan vatten och gummiklipp är kort bör materialet inte innebära mer påverkan än andra material. Uppföljningsstudier av provobjekt där gummiklipp använts som skyddslager i vägar och bankfyllnader visar att metaller och organiska ämnen lakar ut i låga koncentrationer från konstruktionerna.

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  • 48.
    Svedberg, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Miljögeotekniskt bedömningssystem: applikation på väg- och järnvägsbyggnadsmaterial2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [sv]

    Material som används vid väg- och järnvägsbyggnad påverkar och samverkar med den omgivande mark- och vattenmiljön. Att klarlägga och värdera denna påverkan såväl kvantitativt som kvalitativt är av central betydelse för att på ett säkert och bra sätt kunna nyttja traditionella material såväl som till exempel industriella restprodukter. Tyvärr saknas det i Sverige idag ett enhetligt system med bred acceptans för att göra denna typ av bedömningar för väg- och järnvägsbyggnadsmaterial. Detta är olyckligt då det gör att kriterierna eller argumenten vid materialval skiljer sig åt från fall till fall. I denna avhandling beskrivs en miljögeoteknisk modell för enhetlig värdering av emissioner från material i väg- och bankonstruktioner. Modellen utgör en del i "Projekt MGB" vars övergripande syfte är att utarbeta ett enhetligt bedömningssystem. Den föreslagna miljögeotekniska modellen är platsspecifik, beaktar material oavsett dess ursprung och delas in i tre steg; steg 1- Filter, steg 2- Karaktärisering och steg 3- Ställningstagande. I det första steget "filtreras" direkt olämpliga material bort som till exempel farligt avfall och material som saknar dokumentering av egenskaper. Samtidigt ska också gröna material som inte ska beläggas med restriktioner kunna undantas en fortsatt bedömning. De material som blir kvar betraktas som gula material och blir aktuella för fortsatt bedömning för att kunna nyttjas. I det andra steget beskrivs en transportbild baserat på en karaktärisering av den konstruktiva lösningen, dvs användningen (ban- eller vägkonstruktionen) och omgivningen. Vid ställningstagandet, i det tredje steget, sker en värdering av den studerade lösningen mot en kravspecifikation. Denna värdering fungerar som underlag för en klassificering i grön, gul eller röd lösning. Gröna lösningar är förknippade med obetydlig effekt och betraktas som acceptabla med avseende på människors hälsa och miljö. Gula lösningar förknippas med ringa effekt och erfordrar kompletterande kriterier som till exempel resurshushållning och ekonomi före en eventuell acceptans. Röda lösningar betraktas som direkt olämpliga. Studien av modellen visar att det är centralt att inhämta information avseende såväl användningen som omgivningen för att klassificera olika lösningar. Detta gäller inte minst information avseende traditionella material (krossat berg, morän, mm) och speciellt information avseende omgivningens mark- och vattenkemi. Modellen lägger tydligt fokus på de ämnen som kan frigöras och transporteras till omgivningen under anläggningens drifttid. Klassificeringen bör också kompletteras med krav relaterade till kvarlämning, återbruk eller deponering av material efter anläggningens livstid. Allt eftersom modellen används kommer gröna lösningar att identifieras och därmed kommer behovet av nya bedömningar att reduceras. Det inledande filtret är enkelt att tillämpa och kommer att kunna nyttjas av många aktörer, såväl specialister som icke-specialister. De fortsatta stegen, karaktärisering och ställningstagande, har karaktären av ett expertsystem där kompetens inom anläggningsteknik, kemi och hydrogeologi kommer att vara särskilt viktig. Avhandlingen som helhet består av en sammanhållande del samt därutöver 5 rapporter och 2 artiklar.

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  • 49. Forsström, Anna
    Use of thermosyphons in a subarctic climate2002Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In frozen ground, climatic changes and thermal disturbance might cause thawing and degradation of ground previously frozen. Foundations built on frozen ground might be destroyed in a matter of a few seasons. These problems are mostly pronounced in permafrost regions, but also exist in regions with more moderate climates. If thawing takes place the strength of the ground may be greatly reduced. Settlement and stability problems may therefore arise. Insulation, ventilation, or refrigeration systems are used to maintain permafrost locally around foundations. Another possible method to achieve this objective is the use of two-phase thermosyphons. By using this technique heat is transferred from the ground into the air at a higher rate than what would be the case for natural freezing only. A frozen area created in the ground will then increase in size year after year. Ski resorts in Sweden are interested in extending their ski seasons, thereby resulting in a considerable profit for them. In the autumn, the interest is mostly pronounced for cross-country skiing areas. If the ground beneath the ski track could be frozen earlier in the season, the first cover of natural or man-made snow would not easily melt away. In the spring, snow melts earlier in the ski-lift area compared to the ski slopes. If the ground could be kept frozen longer by artificial means and solar radiation is prevented, then the snow would not thaw easily and the ski-lifts could be kept open longer. The aim of this project was two-fold: to examine how well thermosyphons work in Scandinavia and other parts of the world with similar subarctic climates, and to get an insight into the design methods for thermosyphons and their installations. Installations of thermosyphons were done in the autumn of 2000 at two sites in northern Sweden. One thermosyphon was installed in Dundret, Gällivare, which is a ski resort at approximately N67° where the ground temperature as well as the climatic data has been studied. Air and ground temperatures were measured at the second installation at the university campus in Luleå, approximately N66°. This licentiate thesis consists of three parts. A technical report entitled "Ground Freezing with the use of Thermosyphons, Field Tests from an Installation at Dundret, Sweden" is devoted as "Part A", published at Luleå University of Technology, May 2002. In this report the thermosyphon installation in Dundret, Gällivare, Sweden is described. Further, ground temperature measurements for November 2000 to May 2001 and November 2001 have been analysed. In general, temperatures are lower within and closer to the installation than those in the undisturbed ground. A ground temperature difference of -6°C inside the installation area compared to the undisturbed area was observed at certain places throughout the year 2000/2001. The significant artificial cooling was noted at the beginning of February 2001. The conclusions of the study were that thermosyphons work in the climate of northern Sweden. Moreover, "Part B" is a conference paper entitled "Cooling of the Chena Hot Springs Road with thermosyphons", which was submitted and accepted to the 11th International Conference on Cold Regions Engineering in Anchorage, Alaska, May 2002. The Chena Hot Springs Road test section became operational during the autumn of 1998 and includes three test sections underlain with different types of thermosyphons plus a control section. The paper includes a description of the test site and analysis of the ground temperature measurements. It was concluded that thermosyphons could be used to cool the sub-base of the road in order to stabilise the constructions in permafrost areas. The most effective thermosyphon for the middle of the roadway was the AFI Flat unit, and the AFI Buried unit for the edge of the pavement. Lastly, a research report entitled "Ground Thermal Analysis of Thermosyphon Installations", published at Luleå University of Technology, May 2002, is devoted as "Part C" in the thesis. Heat transfer in the ground and at thermosyphon installations are explained in this report. Further, methods for dimensioning thermosyphon installations at buildings and roadways are described. A roadway and a cross-country ski track are both exemplified. In conclusion further work should be performed on developing a thermal analysis program for thermosyphon installations at roadways.

  • 50.
    Pousette, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stabilisering av torv: olika faktorers inverkan på stabiliseringseffekten2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [sv]

    Torvmarker är sättningskänsliga och ej lämpliga att bygga på. Om en väg eller järnväg ska byggas över torvmark måste åtgärder vidtas för att förstärka undergrunden. En metod som har börjat användas de senaste åren är masstabilisering, där ett stabiliseringsmedel blandas ner i torven för att öka dess hållfasthet. Avhandlingen omfattar tre projekt där laboratorie- och fältförsök har utförts på stabiliserad torv. Många faktorer inverkar på den stabiliseringseffekt som erhålls när ett stabiliseringsmedel blandas ner i torv. I detta arbete har de indelats i huvudgrupperna: torvsammansättning, stabiliseringsmedel och utförande. En studie har koncentrerats kring den metodik som används för att tillverka stabiliserade torvprover i laboratoriet. Här är det framförallt faktorer i gruppen utförande som har studerats. I ett andra projekt har en provyta vid Jörn/Lidlund stabiliserats i fält, fältmätningar har utförts, liksom laboratorieförsök på torv från fältlokalen. Faktorer som har varierats är stabiliseringsmedlets sammansättning, mängden stabiliseringsmedel, härdningstid och belastning under härdningstiden. I det tredje projektet har en ca 1 km lång vägsträcka mellan Hemmingsmark och Jävre stabiliserats längs vägens kanter. Vägen går över ett torvlager med en mäktighet av ca 1 m. Fältmätningar har utförts liksom laboratorieförsök. Faktorer som har studerats är bl a tillsatsmedlets sammansättning, torvsammansättning och härdningstid. Stabiliseringseffekten, som uppnås, beror dels av de härdningsprocesser som sker i den stabiliserade torven och dels på hur stor belastning som läggs ut på det stabiliserade området, efter det att stabiliseringsmedlet blandats ner. Avsikten med att belasta området är att komprimera den stabiliserade torven och därmed öka dess hållfasthet. Laboratorieförsök visar att en ökning av belastningen från 20 till 60 kPa kan öka skjuvhållfastheten (uppmätt med hjälp av enaxliga tryckförsök) med 4-6 gånger. Detta kan utnyttjas för att optimera dimensioneringen vid torvstabiliseringsobjekt. Undersökningarna visar att en torvs kemiska sammansättning har avgörande betydelse för erhållen stabiliseringseffekt. Stabiliserade torvprover som har tillverkats och undersökts på identiskt sätt, och där enda variabeln varit torvsammansättningen, gav en skillnad i skjuvhållfasthet (uppmätt med hjälp av enaxliga tryckförsök) på upp till 6 gånger. Ursprungsväxtlighet och humifieringsgrad är två faktorer som bestämmer en torvs kemiska sammansättning och därmed en torvs stabiliseringspotential. En jämförelse mellan låghumifierad vitmosstorv och höghumifierad starrtorv visar att de innehåller olika mycket klasonlignin (en grupp organiska ämnen som bl a innehåller humus- och fulvosyror), ca 35 vikt-% jämfört med ca 60 vikt-% av torrsubstansen. Halten klasonlignin, eller humussyror, kan vara en nyckelparameter som bestämmer en torvs stabiliseringspotential. Låghumifierad vitmosstorv är relativt lätt att stabilisera, medan höghumifierad starrtorv kräver en betydligt större mängd stabiliseringsmedel för att stabiliseras. De stabiliseringsmedel som har använts är olika blandningar av Portlandcement (standard och snabbhärdande) och masugnsslagg (fin- och grovkornig). Fördelarna med att använda masugnsslagg som en komponent i ett stabiliseringsmedel är att avsättning fås för en biprodukt. Det blir billigare än att enbart använda cement och för vissa torvsorter är ett stabiliseringsmedel bestående av en blandning av cement och masugnsslagg effektivare än ett bestående av enbart cement. Det krävs en minsta mängd stabiliseringsmedel för att en stabiliseringseffekt ska erhållas. Denna minsta mängd varierar för olika torvsorter och är lägst för torv med hög stabiliseringspotential. Över denna brytpunkt ökar stabiliseringseffekten med ökad mängd stabiliseringsmedel.

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