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  • 1.
    Bhanbhro, Riaz
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edeskär, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical Behavior of Uniformed Tailings Material in Triaxial Tests2017In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 22, no 06, p. 1717-1730Article in journal (Refereed)
    Abstract [en]

    Tailings dams are raised with time depending upon rate of generation of waste. A tailings dam can contain different particle sized materials within its dam body. The newly raised embankment in a tailings dam can be considered as vertical load being applied on subsequent layer. The applied loads can cause deformations and breakage of particles. The particle breakage can then lead to a skeleton with new particle size particles and hence can lead to new material properties. This paper provides the results from triaxial tests conducted on uniformed particle sizes as, 0.5mm-0.25mm, 0.25mm-0.125mm and 0.125mm-0.063mm.  The tests are performed at various effective radial stresses. The results are evaluated and compared with each particle size. The results include stress-strain and volumetric behavior during shearing, the effective stress ratio and stress-dilatancy plot. The friction angles are also evaluated and compared with different particle sized specimens. It was found that effective stress ratios were slightly higher when tests were performed at lower confining stresses and vice versa. It was also observed that particle size did not show any effect of friction angles.

  • 2.
    Bhanbhro, Riaz
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edeskär, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical Properties of Soft Tailings from a Swedish Tailings Impoundment: Results from Direct Shear Tests2014In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 19, no Z, p. 9023-9039Article in journal (Refereed)
    Abstract [en]

    The shear strength of tailings can vary depending upon the type of ore and method of construction. Tailings dams may possess loose layers in subsequent layers, which may have low shear strength. Since the tailings dams are made-up to last for longer times, the strength parameters and material behaviors are essential to understand, especially potential for static liquefaction in loose layers. This article presents the results from direct shear tests performed on samples from loose layer of a tailings dam. Both drained and undrained tests are carried out. The results indicated the strain hardening behavior in tailings material which indicates loose condition. The shear strength was found to be relatively low as compared to typical values of tailings in literature. A contractant volume behavior was observed for all the tests. During shear tests the vertical height reductions in samples were observed. These changes were significantly increased after peak shear followed by slight increment in pore pressure along shearing angle. The reasons for these height changes are not fully known, but may be a rearrangement in skeleton or breakage of particles during shear which needs further investigative studies.

  • 3.
    Hassellund, Lovisa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Numerical Simulations of Stability of a Gradually Raised Upstream Tailings Dam in Northern Sweden2016In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 21, no 13, p. 4699-4720Article in journal (Refereed)
    Abstract [en]

    This paper presents a case study where numerical modeling, with the finite element method, has been utilized to assess future stability of a tailings dam in Northern Sweden. The finite element software PLAXIS was utilized to simulate future dike raisings for the years 2024 to 2034. The simulations were conducted by computing each dike raising, the subsequent consolidation of the soil and the stability of the dam during the process. The factors of safety directly after each dike raising resulted in values continuously below a recommended value of 1.5. To increase the dam stability, rockfill berms were stepwise added on the downstream slope of the dam. An optimization technique was applied to place as small volumes of rockfill as possible in the berms at the most suitable locations on the downstream slope. By adding various volumes of rockfill in the berms each year, sufficient stability of the dam was obtained in the simulations. The excess pore water pressures increased annually in the simulations. It was shown that the excess pore water pressures did not totally dissipate before the following dike was constructed. The highest excess pore water pressures were located deep in the impoundment and did not have large effects on the dam stability.

  • 4.
    Hidalgo, Kelvis Perez
    et al.
    Boliden Mines Technology.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    3D Numerical Modelling of a Wedge in a Drift at the Kiirunavaara Mine2015In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 20, no 22, p. 12309-12328, article id Paper 2015-0999Article in journal (Refereed)
    Abstract [en]

    historic case is a field study of the mechanics of grouted rockbolts conducted in the Kiirunavaara mine between 1980 and 1983. In the drift the movement of the rock mass was recorded near the wedge, but the detailed behaviour of the wedge was not studied in the historic case. In the present work, the behaviour of the wedge is studied using field deformation measurement data and numerical analysis. The study was aimed at improving the understanding of wedge instability and associated deformations. The study shows that the behaviour of the wedge can successfully be described through evaluation of data obtained from field deformation measurement and numerical analysis. It was found that slip (shear strength reached) developed along the pre-existing joints defining the wedge. Shear deformations were thus non-elastic, but very small, and the wedge remained stable (no fallout).

  • 5.
    Idris, Musa Adebayo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Basarir, Hakan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Wettainen, Thomas
    Luossavaara-Kiirunavaara AB. SE-98381, Malmberget.
    The probabilistic estimation of rock masses properties in Malmberget mine, Sweden2013In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 18, no B, p. 269-287Article in journal (Refereed)
    Abstract [en]

    Numerical modeling techniques have been applied in many mining and civil engineering projects. Traditionally, deterministic methods have been used frequently for the estimation of design or input parameters for numerical modeling. Whereas, it is known that the effect of variability and uncertainty sourced from the complex and variable nature of rock cannot be considered by deterministic approaches using single or mean value. In this paper, the authors tried to apply a probabilistic approach to consider the uncertainties and variability in rock properties. This is to make more a realistic assessment of design parameters of rock masses around an instrumented test drift in Malmberget Mine within the content of the “Rock mass - Rock support interaction project” conducted at the Division of Mining and Geotechnical Engineering, Lulea University of Technology. To calculate the design parameters GSI of rock mass, UCS and mi constant of the intact rock are considered as random variables. For each of these random variables ranges were specified depending on the laboratory and field information. Using Monte Carlo simulation method a possible range of each of necessary strength and deformability properties were obtained and presented. The assessed values can be used as preliminary input parameters and considered as basis for further numerical modeling calibration studies.

  • 6.
    Idris, Musa Adebayo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Saiang, David
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Comparison of different probabilistic methods for analyzing stability of underground rock excavations2016In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 21, no 21, p. 6555-6585Article in journal (Refereed)
    Abstract [en]

    Stability analyses of underground rock excavations are often performed using traditional deterministic methods. In deterministic methods the mean or characteristics values of the input parameters are used for the analyses. These method neglect the inherent variability of the rock mass properties in the analyses and the results could be misleading. Therefore, for a realistic stability analyses probabilistic methods, which consider the inherent variability of the rock mass properties, are considered appropriate. A number of probabilistic methods, each based on different theories and assumptions have been developed for the analysis of geotechnical problems. Geotechnical engineers must therefore choose appropriate probabilistic method to achieve a specific objective while taking into account simplicity, accuracy and time efficiency. In this study finite difference method was combined with five different probabilistic methods to analyze the stability of an underground rock excavation. The probabilistic methods considered were the Point Estimate Method (PEM), the Response Surface Method (RSM), the Artificial Neural Network (ANN), the Monte Carlos Simulation (MCS), and the Strength Classification Method (SCM). The results and the relative merits of the methods were compared. Also the general advantages of the probabilistic method over the deterministic method were discussed. Though the methods presented in this study are not exhaustive, the results of this study will assist in the choice of appropriate probabilistic methods for the analysis of underground rock excavations. 

  • 7.
    Jia, Qi
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Yang, Qixing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Guo, Lijie
    Beijing General Research Institute of Mining and Metallurgy.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Xue, Peng
    Department of Ferrous Metallurgy, School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing.
    Liu, Guiqun
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Jiang, Liang
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. jiang.liang@ltu.se .
    Effects of fine content, binder type and porosity on mechanical properties of cemented paste backfill with co-deposition of tailings sand and smelter slag2016In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 21, no 20, p. 6971-6988Article in journal (Refereed)
    Abstract [en]

    Mine backfilling is a process where the underground voids resulted from mining are filled with waste materials. The potential of co-depositing iron sand produced from smelting process with tailings sand was investigated in the present study. Different amounts of iron sand were mixed with the tailings sand to prepare cemented paste backfill (CPB) samples. Two types of binders were used. Uniaxial compression tests were performed for the CPB samples after 28 days of curing. The porosities of the samplers after curing were calculated to correlate the porosity with the uniaxial compression strength, UCS. Results from uniaxial compression tests showed that the amount of iron sand and the type of the binder influences the UCS, as well as content values of fines and porosity. These results demonstrated the possibility for a part of Fe-sand to be deposited together with the tailings sand to increase UCS values for the CPB samples, which will be beneficial for both mining operation and environmental protection.

  • 8.
    Johansson, Jens
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edeskär, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effects of external water-level fluctuations on slope stability2014In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 19, no K, p. 2437-2463Article in journal (Refereed)
    Abstract [en]

    There is a worldwide increasing need of land-use in costal/waterfront areas. All kinds of changes of geotechnical conditions in these areas pose potentially slope instability and jeopardized values of property and life. Soil slopes are affected by water-level fluctuations originating from as well tides and other waves, as non-natural sources such as watercourse regulation for irrigation, freshwater provision, and/or hydropower production. Due to a growing use of non-regulated energy sources (e.g. wind and solar), the need of energy balancing and storage is increasing. Also techniques such as pumped hydropower storage (PHS), which may be associated with significant water-volume changes in the reservoirs, are growing globally. This is expected to involve variations of hydropower reservoir water levels; hour to hour, day to day and/or seasonally. In this paper geotechnical effects of water-level fluctuations on slope stability are reviewed; relevant inter-disciplinary findings are presented, adventurous simplifications and/or inadvertencies are underlined, and potential improvement areas are identified. A lot of research has been carried out focused on coastal erosion; mainly aimed to investigate tide-water influence on slope-profile development, and quantification of sediment production. On the other hand, studies on effects of water-level changes on geotechnical conditions in adjacent soil structures have been predominantly concerning embankment dams. In addition, studies addressing processes in natural slopes and banks are often environmentally oriented, rather than focused on slope stability. Since also water-level rise (not only drawdown) has been shown to significantly influence slope stability, further investigation of processes of suction loss, effects of rapidly increased water pressures, and retrogressive failure development is needed. Long-term views are often missing; analyses tend to involve few rise-drawdown cycles, soil materials are deficiently described, and limited attention is put on constitutive models used. Reliable integration of seepage effects on soil-property changing requires consideration of as well acute effects as long-term changes. Therefore, proper consideration of internal erosion is central. Given the critical relationship between pore pressure, soil strength, and soil-deformation, analyses have to be performed using robust simulation approaches. The terms “simplicity” and “applicability”—promoting use of limit-equilibrium methods—should more often be set in relation to accuracy and robustness provided by use of methods considering also deformations.

  • 9. Mainali, Ganesh
    et al.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Thunehed, Hans
    Geovista AB.
    Tailings dams monitoring in Swedish mines using self-potential and electrical resistivity methods2015In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 20, no 13, p. 5859-5875Article in journal (Refereed)
    Abstract [en]

    Tailings dam failures have been occurring in recent years. Many of these failures have caused human casualties, destruction of property, and damage to environment and huge economic loss to the mining industry. The monitoring of the dam is essential to know the existing state of the dams and to ensure the safety of the dam over its life time. The present study has been conducted to test the applicability of electrical resistivity and self-potential (SP), for detecting anomalous seepage through mine tailings dams in Sweden and monitoring the physical condition of the dam. This study has demonstrated the potential of using geoelectrical methods for monitoring the conditions of the tailing dams related to seepage.

  • 10.
    Makusa, Gregory Paul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Verification of field settlement of in-situ stabilized dredged sediments using cone penetration test data2012In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 17, no Y, p. 3665-3680Article in journal (Refereed)
    Abstract [en]

    Utilization of in-situ mass stabilization for geotechnical applications is increasing. Laboratory tests may have drawbacks on valuations of engineering parameters for estimations of settlement of in-situ stabilized soil mass. Factors such as compression, mixing work, homogeneity and curing temperature may influence the differences in mechanical properties between laboratory test results and achieved field values. Therefore, utilization of appropriate in-situ mechanical parameters may be required during design analyses. Various in-situ tests are available for use in geotechnical context. Among others, cone penetration test (CPT) is one of most widely used in-situ tests. Numerous CPT empirical correlations are available for use in conventional soils. Utilization of such CPT empirical correlations for in-situ stabilized soils has to be examined. In this paper, the in-situ constrained modulus was evaluated using conventional CPT empirical correlation and utilized as oedometer modulus in finite element analysis for estimation of settlement of preloaded in-situ stabilized dredged sediments. The results show that, computed settlement values fall within the range of measured one. These findings suggest that, the cone penetration test and its empirical correlations, which were established for conventional soils, can also be utilized in stabilized soils.

  • 11.
    Ormann, Linda
    et al.
    Geotechnical Engineer, SWECO Infrastructure AB, Gjörwellsgatan 22, Stockholm.
    Zardari, Muhammad
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Bjelkevik, Annika
    Geotechnical Engineer, SWECO Infrastructure AB, Gjörwellsgatan 22, Stockholm.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Numerical analysis of curved embankment of an upstream tailings dam2011In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 16, no I, p. 931-944Article in journal (Refereed)
    Abstract [en]

    A curved embankment (corner) of an upstream tailings dam was analyzed with the finite element method to identify possible zones of low compressive stresses susceptible to hydraulic fracturing that might initiate internal erosion. The embankment was also analyzed as a straight section, with the same cross section as in the corner, in order to compare compressive stresses in the corner and the straight section. The analysis showed that in comparison to the straight section of the dam, the compressive stresses in the corner were (i) much lower above the phreatic level, in the rockfill banks and the filter zones, and (ii) fairly lower below the phreatic level. The rockfill and the filter contain coarse materials, which are not sensitive to hydraulic fracturing and internal erosion. An increase in radius of the corner is proposed to avoid too low compressive stresses that may develop due to future raisings. The slope stability analysis showed that the corner is currently stable, but an additional rock fill bank on the downstream toe is required for future raisings.

  • 12.
    Petropoulos, Nikolaos
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mihaylov, Dimitar
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Johansson, Daniel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Nordlund, Erling
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A Suggested Method for the Study of Crushed Aggregate Response to Dynamic Compaction2017In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 22, no 02, p. 387-406Article in journal (Refereed)
    Abstract [en]

    Soil improvement by dynamic compaction has been extensively used all around the world in large civil engineering projects. Limited number of laboratory tests has been conducted to study the behavior of soil material under dynamic loading. A suggested method is presented in this paper which includes a new laboratory apparatus and experimental procedure as well as data analysis. The suggested impact machine is a drop hammer type machine, it can host up to 37.5 mm particle size in a coarse-grained aggregate matrix independent of its conditions, i.e. saturated or unsaturated, it is also flexible in terms of weight and size of the drop hammer and the mold. The machine is equipped with accelerometers for continuous monitoring of the sample’s behavior during impact. The experimental procedure shows the steps for conducting consistent dynamic compaction tests. It also describes how the measurements should be conducted. These measured quantities correspond to key parameters such as density, angle of repose and compaction. Finally, a case example demonstrates the function of the machine and the analysis of the recorded data.

  • 13.
    Rodriguez, Juan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Edeskär, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Particle shape quantities and measurement techniques: a review2013In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 18/A, p. 169-198Article in journal (Refereed)
    Abstract [en]

    It has been shown in the early 20th century that particle shape has an influence on geotechnical properties. 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. This literature review covers different methods and techniques used to determine the geometrical shape of the particles. Particle shape could be classifying in three categories; sphericity - the overall particle shape and similitude with a sphere, roundness - the description of the particle’s corners and roughness - the surface texture of the particle. Thecategories are scale dependent and the major scale is to sphericity while the minor belongs to roughness. The overview has shown that there is no agreement on the usage of the descriptors and is not clear which descriptor is the best. One problem has been in a large scale classify shape properties. Image analysis seems according to the review to be a promising tool, it has advantages as low time consumption or repeatability. But the resolution in the processed image needs to be considered since it influences descriptors such as e.g. the perimeter. Shape definitions and its potential role in soil mechanics are discussed.

  • 14.
    Rönnqvist, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratory testing of internal stability of glacial tills: a review2014In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 19, no V, p. 6315-6336Article in journal (Refereed)
    Abstract [en]

    Suffusion is an initiation mechanism of internal erosion. A soil susceptible to suffusion is internally unstable. In such a soil there is an imbalance between the finer fraction and the coarser, allowing for non-structural fine-grained particles in between fixed structural coarser grains. Thus, the fines may migrate which initiate internal erosion. This paper discusses internal stability of soils in general, and glacial till bases in particular, and reviews available laboratory testing in the literature on this type of soil. The laboratory set-up, characteristics of soils tested, soil preparation and boundary conditions are among the aspects discussed. The paper concludes with recommendations for further research in terms of glacial tills and internal stability testing.

  • 15.
    Vahdati, Pooya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Levasseur, Séverine
    Département ArGEnCo Service de Géomécanique et géologie de l'ingénieur Université de Liège.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Inverse Hardening Soil Parameter Identification of an Earth and Rockfill Dam by Genetic Algorithm Optimization2014In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 19, no N, p. 3327-3349Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of identification of constitutive parameter values in the Hardening soil model by inverse analysis of an earth and rockfill dam application. The authors have experience from a previous study on the same case with the Mohr-Coulomb model. The objective of this research is to examine if the inverse analysis technique can be successfully used for this type of application and choice of constitutive model. The values of soil parameters are determined based on horizontal deformations obtained from installed instrumentations in the dam. The quantities that are monitored in the dam can be numerically predicted by a finite element simulation. In inverse analysis, constitutive parameter values are chosen in such a way that the error between data recorded by measurements in the dam and numerical simulation is minimized. An optimization method based on the genetic algorithm was applied to search for the minimum error in the search domain in this study. Optimizations have initially been performed in a large search domain in order to find a criterion identifying the best solutions. Thereafter, the optimizations were limited to this criterion in order to find the best set of solutions close to the optimum point. Moreover, the error function topology and smoothness was examined as well. It was overall concluded, that the inverse analysis technique could be effectively used for earth and rockfill dam applications, despite the fact that the technique is expensive in terms of computational time.

  • 16.
    Vahdati, Pooya
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Levasseur, Séverine
    Département ArGEnCo Service de Géomécanique et géologie de l'ingénieur Université de Liège.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Inverse Mohr-Coulomb soil parameter identification of an earth and rockfill dam by genetic algorithm optimization2013In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 18, no X, p. 5419-5440Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of identification of constitutive parameter values in the Mohr-Coulomb model by inverse analysis of an earth and rockfill dam application. The objective is to examine if the technique of inverse analysis can be effectively used for this type of case. The values of soil parameters are determined based on horizontal deformations recorded from installed instrumentations in the dam. The quantities that are monitored in the dam can be numerically predicted by a finite element simulation. In inverse analysis, constitutive parameter values are chosen in such a way that the error between data obtained by measurements in the dam and numerical simulation is minimized. An optimization method based on the genetic algorithm was utilized to search for the minimum error in this study. Optimizations have been performed against both a synthetic and a real dam case. The effect of the population size in the genetic algorithm was also analysed for this case in order to approach a proper set of solutions close to the optimum point by considering: the finite element computation time and the error function values. The error function topology was examined as well, and it was found to be complex and noisy for this application. The genetic algorithm is known to be a practically good choice of search method for such complicated topologies. It was overall concluded, that the inverse analysis technique studied, could be effectively used for this kind of earth and rockfill dam application despite the fact that, the technique is expensive in terms of computational costs. Inverse analysis has the potential to become a valuable tool for dam engineers assessing dam performance and dam safety if it becomes readily available in commercial finite element software.

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