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  • 1.
    Barabadi, Abbas
    et al.
    Tromsø University, Department of Engineering and Safety, UiT The Arctic University of Norway, Tromsø.
    Garmabaki, Amir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Zaki, Rezgar
    Department of Engineering and Safety, UiT The Arctic University of Norway, Tromsø.
    Designing for performability: An icing risk index for Arctic Offshore2016In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 124, p. 77-86Article in journal (Refereed)
    Abstract [en]

    Ice accretion affects the performability of offshore production facilities in various ways, including repair time and failure rate. It can increase power losses, life cycle costs and safety hazards. There are few studies and limited systematically collected information about the impact of ice accretion on performability and its attributes (reliability, maintainability, quality, safety and sustainability) for Arctic offshore production facilities. This paper will discuss the effects of different types of ice accretion on the performability of Arctic offshore production facilities. Then, to quantify their effect on the performability of offshore production facilities, an icing risk index is developed; its application is then shown by means of a case study.

  • 2.
    Bengtsson, Lars
    Luleå tekniska universitet.
    Percolation of meltwater through a snowpack1982In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 6, no 1, p. 73-81Article in journal (Refereed)
    Abstract [en]

    The hydraulics of meltwater percolation through a snowpack is analyzed in some detail. An implicit numerical model is used for determining the meltwater movement. The effect of freezing fronts of the free liquid water in the snowpack is evaluated. It is shown that even after a moderately cold night, it takes several hours of snowmelt before the snowpack again reaches its irreducible liquid content. The meltwater flux front moves very slowly down through the depth, where the liquid water has been refrozen during a preceding night. The time delay between the initiation of snowmelt at the surface and the start of run-off at the base of the snowpack is shown to be determined from a simple continuity reasoning. Finally, a comparison between theory and field measurements is made.

  • 3.
    Bhardwaj, Anshuman
    et al.
    Department of Natural Resources, TERI University, New Delhi.
    Joshi, Prakash C.
    Space Applications Centre, ISRO, Ahmedabad, Atmospheric and Oceanic Sciences Group, Space Applications Centre, Indian Space Research Organisation, Ahmedabad, Department of Natural Resources, TERI University, New Delhi.
    Snehmani, Snehmani
    Snow and Avalanche Study Establishment, Defence Research and Development Organization (DRDO), Him Parisar, Sector-37A, Chandigarh.
    Singh, Mritunjay Kumar
    Snow and Avalanche Study Establishment, Defence Research and Development Organization (DRDO), Him Parisar, Sector-37A, Chandigarh.
    Sam, Lydia
    Department of Environmental Science, Sharda University.
    Gupta, R.D.
    Snow and Avalanche Study Establishment, Defence Research and Development Organization (DRDO), Him Parisar, Sector-37A, Chandigarh, Motilal Nehru National Institute of Technology (MNNIT), Allahabad.
    Mapping debris-covered glaciers and identifying factors affecting the accuracy2014In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 106-107, p. 161-174Article in journal (Refereed)
    Abstract [en]

    Supraglacial debris significantly hampers the mapping of glaciers using remote sensing data. A semi-automated approach for the mapping of debris-covered glacier was applied, which combined the inputs from thermal and optical remote sensing data and the Digital Elevation Model (DEM) derived morphometric parameters. A thermal mask that delineates the supraglacial debris extent was generated by the thresholding of surface temperature layer obtained from Landsat TM/ETM. + thermal band satellite data. The extent of clean glacier ice was identified by band ratioing and thresholding of TM/ETM. + 4 and TM/ETM. + 5 bands. Morphometric parameters like slope, plan curvature and profile curvature were rearranged in similar surface groups using the technique of cluster analysis. All these masks were vectorized and final classification maps were generated using geographic information system (GIS) overlay operations. The areal extent of semi-automated outlines of Hamtah and Patsio Glaciers derived from cluster analysis varied from manually derived outline using pan-sharpened Landsat ETM. + September 2000 image by -. 1.3% and -. 1.6%, respectively. Year 2011 classification map for Patsio Glacier was compared with the field observations and a high correlation and overall accuracy (~. 91%) were observed. The same classification methodology was adopted for images of years 2000 and 1989 for Patsio Glacier to observe the effects of varying snow cover patterns on adopted methodology. Also the methodology was adopted and verified for Hamtah Glacier, with different geometry and terrain conditions as compared to Patsio Glacier. Although the spatial resolution limitation of ASTER GDEM and Landsat TM/ETM. + thermal band limits the automated mapping of small debris-covered glaciers, the outcomes are still favorable enough to apply such methodologies for mapping different types of debris-covered glaciers in the future

  • 4.
    Bonath, Victoria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Edeskär, Tommy
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Lintzén, Nina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Fransson, Lennart
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Properties of ice from first-year ridges in the Barents Sea and Fram Strait2019In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 168, article id 102890Article in journal (Refereed)
    Abstract [en]

    First-year ice ridges are one of the main load scenarios that off-shore structures and vessels operating in ice-covered waters have to be designed for. For simulating such load scenarios, the knowledge gap on ice mechanical properties from the consolidated part of first-year ridges has to be filled. In total 410 small-scale uniaxial compression tests were conducted at different strain rates and ice temperatures on ice from the consolidated layer of 6 different first-year ridges in the sea around Svalbard. For the first time uniaxial tensile tests were performed on ice from first-year ridges using a new testing method. Ice strength was evaluated for different ice type, which are determined for each specimen based on a proposed ice classification system for ice from first-year ridges. 78% of all samples contained mixed ice with various compounds of brecciated columnar and granular ice. Ice strength of mixed ice showed isotropy, except for the samples containing mainly columnar ice crystals. For horizontal loading, mixed ice was stronger than columnar and granular ice. The residual strength of ductile ice depended on the strain rate. At 1.5% strain remained 70% of peak strength at 10−4 s−1 and 50% at 10−3 s−1. Ductile failure dominated for 75% of all mixed ice tests at 10−3 s−1 and − 10 °C. Ductile compressive strength was generally higher than brittle compressive strength for mixed ice. Brine volume was the main parameter influencing the tensile strength of the mixed ice which was between 0.14 MPa and 0.78 MPa measured at constant ice temperature of −10 °C.

  • 5.
    Bonath, Victoria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Petrich, Chris
    Northern Research Institute Narvik.
    Sand, Bjørnar
    Northern Research Institute Narvik.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Cwirzen, Andrzej
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Morphology, internal structure and formation of ice ridges in the sea around Svalbard2018In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 155, p. 263-279Article in journal (Refereed)
    Abstract [en]

    The results from 3 years of comprehensive field investigations on first-year ice ridges in the Arctic are presented in this paper. The scopes of these investigations were to fill existing knowledge gaps on ice ridges, gain understanding on ridge characteristics and study internal properties of ice. The ability of developing reliable simulations and load predictions for ridge-structure interactions is the final principal purpose, but beyond the scope of this paper. The presented data comprise ridge geometry, ice block dimensions from ridge sails, ice structure in the ridge and values on the ridge porosity and the degree of consolidation. The total ridge thickness conformed to other ridges studied in the same regions. The consolidated layer thickness was on average 2–3 times the level ice thickness. Minimum 33% and in average 90% of the ridge keel area was consolidated. The distribution of ice block sizes and block shapes within a ridge appears to be predictable. A new approach for deriving a possible ridging scenario and ridge age is presented. Different steps of the ridge building process were identified, which are in good agreement with earlier simulated ridging events. After formation of very thin lead ice between two floes deformation occurs through rafting and ridging until closure of the lead. Subsequently the adjacent level ice floe fractures proceeding ridge formation until ridging forces exceed driving forces. A time span of 10 days could be assessed for a possible ridge formation date, estimating the ridge age of the studied ridge located east of Edgeøya at 78° N to be 7 to 8 weeks.

  • 6.
    Dagli, Deniz
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Zeinali, Amin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Image analyses of frost heave mechanisms based on freezing tests with free access to water2018In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 146, p. 187-198Article in journal (Refereed)
    Abstract [en]

    A freezing test apparatus was supplemented with a camera to allow for recording and monitoring one-dimensional freezing tests to analyze the development of ice lenses via particle image velocimetry (PIV) in the laboratory. Two tests on disturbed, partially saturated samples of silt loam were conducted. 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. Test results were also used to establish a qualitative relationship between heat extraction and heave rates. Advantages and disadvantages of utilizing image analysis methods were discussed. Potential remedies for overcoming the drawbacks of using image analysis are suggested.

    Image analysis is shown to be a viable method in further understanding of frost heave mechanisms.

  • 7.
    Hellgren, Rikard
    et al.
    KTH Royal Institute of Technology, Department of Civil and Architectural Engineering, Stockholm, Sweden.
    Malm, Richard
    KTH Royal Institute of Technology, Department of Civil and Architectural Engineering, Stockholm, Sweden.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Johansson, Fredrik
    KTH Royal Institute of Technology, Department of Civil and Architectural Engineering, Stockholm, Sweden.
    Nordström, Erik
    KTH Royal Institute of Technology, Department of Civil and Architectural Engineering, Stockholm, Sweden.
    Wilde, Marie Westberg
    KTH Royal Institute of Technology, Department of Civil and Architectural Engineering, Stockholm, Sweden.
    Measurement of ice pressure on a concrete dam with a prototype ice load panel2020In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 170, article id 102923Article in journal (Refereed)
    Abstract [en]

    This paper presents the development and installation of a prototype ice load panel and measurements of ice load from February 2016 to February 2018 at the Rätan hydropower dam in Sweden. The design of the 1 × 3 m2 panel enables direct measurement of ice pressure on the concrete surface is based on previous experience from similar measurements with sea ice. Important features of the design are sufficient height and width to reduce scale effects and to cover the ice thickness and variations in water level. The Rätan dam was chosen based on several criteria so that the ice load is considered to be reasonably idealized against the dam structure.

    For the three winters 2016, 2016/2017, 2017/2018, the maximum ice load recorded was 161 kN/m, 164 kN/m and 61 kN/m respectively. There were significant daily fluctuations during the cold winter months, and the daily peak ice loads showed a visual correlation with the daily average temperature and with the daily pattern of operation of the power station with its corresponding water level variations.

  • 8.
    Knutsson, Roger
    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.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    How to avoid permafrost while depositing tailings in cold climate2018In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 153, p. 86-96Article in journal (Refereed)
    Abstract [en]

    Managing tailings deposition in cold climate requires specific measures not to create permafrost. The risk of generating permafrost due to tailings deposition exists even in regions where permafrost would naturally not occur. Material being frozen during winter might not fully thaw in the following summer due to added height of the tailings on the surface. Such embedded layers of permafrost should be avoided especially close to tailing dams. Main reasons are to prevent impermeable layers in tailings facilities, and to reduce the risk of having implications if such layers thaw during warmer summers causing increase in pore water pressure, reduced effective stress, and increased water content.

    This paper presents a numerical study on the effects of tailings deposition in cold regions in relation to the potential formation of permafrost. Various deposition rates, schedules and tailings properties were evaluated. One-dimensional heat conduction analyses were performed with a temperature scenario representing a mine district in northern Sweden. Results show, that the thickness of permafrost layers increase with increased deposition rate and with increased water content. It was also shown that wet and loose tailings must be deposited in short periods during summer to avoid permafrost generation. In the case of dry and dense tailings more time is available for deposition in order not to cause aggradation of permafrost in the deposit.

    These findings can help mining operation to set up deposition schedules for tailings facilities in cold climate. For known tailings properties, results can be used to identify periods of the year when, and how much, tailings can be deposited in critical areas of a deposit in order to avoid permafrost formation.

  • 9.
    Lintzén, Nina
    et al.
    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.
    Snow storage: modelling, theory and some new research2018In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 153, p. 45-54Article in journal (Refereed)
    Abstract [en]

    The arrival of natural snow is often delayed nowadays due to global warming. This causes problems for ski resorts and other places where winter activities in different forms take place. Storing snow provides one solution for the winter business industry to deal with this problem. However, there is so far very little research concerning this question. In this paper a review of current knowledge of snow storage and experiences from mainly Scandinavian snow storages is presented. New results concerning melting losses of stored snow from a trial experiment in the north of Sweden are presented. These results are compared to theoretical calculations. The model used for the calculations is shown to be useful for estimating melting losses of insulated piles of snow. Thus the calculations can serve as an important background when designing an insulated snow depot. The model can also be used to compare different insulating materials and to determine properties such as thickness of the insulating layer needed to sufficiently insulate the snow. By minimizing the surface area of insulated snow depots, melt rate due to heat from the air, sun and sky, which constitute the largest part of the total melt, can be reduced. The quality of insulating materials used will be subject to annual observation. Commonly used insulating materials such as bark, wood chips, cutter shavings and sawdust deteriorate.

  • 10.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Laboratory calibration of TDR-probes for snow wetness measurements1997In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 25, no 3, p. 197-205Article in journal (Refereed)
    Abstract [en]

    In situ registration of snow liquid water content for avalanche protection and snow-melt prognosis is much needed. The Time Domain Reflectometry (TDR) method is a possible method to meet this need. Laboratory comparison of the TDR-method with the dilution method shows that the TDR-method has the potential to register variations in snow liquid water content down to 1-2 vol.%. It should be possible to achieve continuous registration of snow-pack wetness with a spatial resolution down to approximately 5 cm with several sets of TDR-probes (mounted with 3 cm vertical and 5 cm horizontal distance) combined with a multiplexer and a storage unit. For application when changes in snow density are great (as with newly fallen snow) the method has to be combined with separate density determinations. The dielectric constant of night-time refrozen snow can be used for density determination.

  • 11.
    Mainali, Ganesh
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Dineva, Savka
    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.
    Experimental study on debonding of shotcrete with acoustic emission during freezing and thawing cycle2015In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 111, p. 1-12Article in journal (Refereed)
    Abstract [en]

    tudying the deterioration of shotcrete due to freezing and thawing is important for improvement of the understanding of the failure mechanisms/debonding of shotcrete in cold regions. Water leakage in a tunnel leads to ice growth during freezing temperature and ultimately creates favorable environment for fallouts of shotcrete and rock. Repeated freezing and thawing of shotcrete lead to development of new micro cracks and propagation of pre-existing micro cracks. In this study, test panels of granite with dimension 800 x 800 x 80 mm covered with 50-mm thick shotcrete were subjected to freezing and thawing action in a controlled environment. The initiation and the development of freeze-induced micro cracks in shotcrete-rock interface were studied by continuously monitoring acoustic emissions (AE) and temperature. The clustering of the AE events during freezing and thawing indicates that micro cracks appeared in the shotcrete-rock interface and caused adhesion failure. The larger number of AE events in the panels, with access to water during freezing, confirmed that water contributes to material deterioration and also reduces the adhesive strength. The test results showed that most of the acoustic emission occurred during the freezing cycle and the number of acoustic emission events did not increase with the successive increase of the number of freezing and thawing cycles.

  • 12. Maurice, Christian
    et al.
    Lagerkvist, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    LFG emission measurements in cold climatic conditions: seasonal variations and methane emissions mitigation2003In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 36, no 1-3, p. 37-46Article in journal (Refereed)
    Abstract [en]

    Landfill gas (LFG) emissions were measured at three landfills in Northern Sweden and Northern Finland. Several strategies for measuring gas emissions in winter conditions (i.e., a snow-covered surface and frozen ground) were tested. Static chambers appeared to be the most suitable measurement technique. The study results showed that winter measurements should be done directly at the soil surface and that any snow cover should be removed beforehand. A seasonal variation of the emissions was observed. Methane emissions were measured during late winter at the three sites and during late summer at two of the same three sites. Monitoring performed during the different seasons yields a better estimation of the annual LFG emissions. Variations in methane oxidation are likely sources of any differences as low temperature and low soil water content both reduce methane oxidation activity. At low emission rates, the main methane emission may occur during wintertime because of the mitigation effect landfill cover has on methane oxidation during summertime. A reduced methane oxidation activity was observed during the late summer at two of the sites. A combination of summer dryness and heat from methane oxidation is believed to have dried the soil, which then caused a subsequent decrease in methane oxidation. To use landfill covers for the management of methane emissions in cold climates, special consideration must be given to the moisture and extreme low temperature factors.

  • 13.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Measurement of P -T coexistence curve for ice-water mixture1990In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 19, no 1, p. 83-88Article in journal (Refereed)
    Abstract [en]

    The pressure-melting curve of ice is often found in literature dealing with ice problems. This curve originates from the excellent experimental works of G. Tammann* and P.V. Bridgman**. The method used means that ice at constant temperature is submitted to an external pressure. When increasing the pressure a sudden volume change occurs, the pressure-melting point is reached. Results from their works are summarized in this paper. An alternative experimental method was used in this study. Water is confined in a filled-up pressure tank. The water is then cooled from an initial temperature of 0°C. The ice formed creates a pressure increase in the ice-water mixture. At any temperature a corresponding pressure occurs at phase equilibrium. The temperature and the pressure are measured in the ice-water mixture. The results are in good agreement with earlier measurements. The method used, which is easy to handle even with this prototype equipment, should be more accurate than the old method since one possible source of error (the external pressure) is eliminated. The method could be used for other substances than pure water.

  • 14.
    Nordell, Bo
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerström, Göran
    Method for continuous measurement of ice cover thickness1995In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 23, no 4, p. 389-391Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to evaluate a method for continuous measurement of ice cover thickness. The measuring device consists of a water-filled bucket, floating with its brim at the water surface. A pipe is vertically mounted at the centre of the bucket and capped with an oil-filled balloon. The volume expansion of the formed ice results in a corresponding oil flow, from the balloon at the bottom of the bucket through the pipe into an expansion bucket above ground. By measuring the volume expansion continuously, the ice thickness can be determined at any time. The performance of preliminary laboratory tests confirmed the feasibility of the method.

  • 15.
    Petrich, Christian
    et al.
    Norut Northern Research Institute, Narvik.
    Sæther, Irina
    Norut Northern Research Institute, Narvik.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sand, Björnar
    Norut Northern Research Institute, Narvik.
    Arntsen, Bård
    Norut Northern Research Institute, Narvik.
    Time-dependent spatial distribution of thermal stresses in the ice cover of a small reservoir2015In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 120, p. 35-44Article in journal (Refereed)
    Abstract [en]

    Static ice loads (ice actions) are a key design parameter for dams in cold climates. However, their theoretical description is still elusive, introducing uncertainty in design and hindering development of remediation measures. We present and analyze measurements of stresses due to thermal loads in a small reservoir in northern Norway. Several weeks of observations, including both cold and warm spells, were well-described by a simple equation that accounts for thermal expansion and temperature-dependent creep. One model parameter was found to depend systematically on the location of measurements within the reservoir. Biaxial stress measurements showed that the stress field was not homogeneous. Results suggest that the stress field in reservoirs should be predictable from first principles with numerical methods and point toward a promising, simple parameterization.

  • 16.
    Riska, K.
    et al.
    Total SA E&P, Uganda.
    Bridges, R.
    Total SA E&P, Uganda.
    Shumovskiy, S.
    Yamal LNG, Russia.
    Thomas, C.
    Yamal LNG, Russia.
    Coche, E.
    Total SA E&P, Uganda.
    Bonath, Victoria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Tobie, A.
    Stagiare at Total SA, France.
    Chomatas, K.
    Stagiare at Total SA, France.
    Caloba Duarte de Oliveira, R.
    Stagiare at Total SA, France.
    Brash ice growth model: development and validation2019In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 157, p. 30-41Article in journal (Refereed)
    Abstract [en]

    Brash ice growth in frequently navigated areas like fairways or ports is quick due to the ‘freezing – breaking’ cycle induced by sub-zero temperatures and ship traffic. This problem is very acute in ports in Arctic areas where the temperatures are very low for long durations and the ship traffic is frequent. In order to take adequate action in managing the brash ice, the forecasts of the amount of brash ice expected should be reliable. The aim of this work is to develop and validate these prediction methods.

    The growth model developed is based on extension of earlier growth models which modify the Stefan type growth modelling. The improvement on the earlier models is that the brash ice layer is divided into three layers (instead of two in earlier models): The consolidated layer just below the water level, the brash ice over the water level and the unfrozen brash ice below the consolidated layer. The thermodynamic model follows the Stefan formulation including only the heat flux from latent heat release upon freezing (Stefan, 1891 and e.g. Anderson, 1961). The modelling includes the cyclic breaking and refreezing.

    The validation of the model is made using measurements carried out in winter 2013 in Luleå port and in winter 2015 in Sabetta in the Yamal peninsula. Luleå data suggests that the sideways motion of brash ice due to ship motion and wake should be taken into account when assessing the brash ice thickness. The analytical calculation over-estimates the brash ice thickness in the actual channel but under-estimates the total amount of broken ice. When applied to Sabetta data, the analytical calculation predicts well the observed brash ice thickness. It can be concluded that the analytical method that does not take into account any radiation heat fluxes can be applied in the high Arctic where solar radiation plays a minor role and ice surface is clearly below zero.

  • 17.
    Semadeni-Davies, Annette
    et al.
    Department of Water Resources Engineering, Lund University.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bengtsson, Lars
    Department of Water Resources Engineering, Lund University.
    Radiation balance of urban snow: a water management perspective2001In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 33, no 1, p. 59-76Article in journal (Refereed)
    Abstract [en]

    The radiation balance of urbanised catchments differs from their rural counterparts, with snowpacks experiencing either enhanced or decreased irradiance depending on snowpack location and condition. As snowmelt is largely driven by radiation inputs, changes to localised irradiance (and melt rates) have implications for urban runoff generation. Storm- and wastewater drainage systems in cold regions are currently dimensioned for rain according to practices developed for temperate climates. They are not designed to cope with wintry conditions, which can lead to surface flooding, hydraulic overloads and poor water quality at receiving waters. Net allwave radiation measurements over snow made at the Swedish city of Luleå during April 1997 and 1998 are presented. The 1997 measurements were made in the vicinity of a matt-black-painted metal building at Luleå University of Technology, whereas the 1998 measurements are from a specially constructed 3×6-m black plastic-clad wall built on an open field just outside the town. Black minimises multiple reflections between the snow and walls, while maximising absorption of shortwave radiation by walls. The data were compared to the outputs of an urban radiation model. The results show that urban structures significantly alter radiation over snow. The temperature of the south-facing walls translates to longwave enhancements in the order of 150 W m−2 for several metres from the walls on sunny days. Shaded snow near the north-facing wall showed a net allwave radiation loss of the same order of magnitude. Radiation inputs to snow are similar both to the north and south of walls when the sky is overcast. The need to include snowmelt energetics within design and management techniques is discussed in light of the results.

  • 18.
    Skogsberg, Kjell
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    The Sundsvall Regional Hospital snow cooling plant: results from the first year of operation2002In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 34, no 2, p. 135-142Article in journal (Refereed)
    Abstract [en]

    During the summer of 2000, the Sundsvall Regional Hospital (central Sweden) required 655 MW h of comfort cooling with a maximum cooling power of 1366 kW. Of the cooling demand, approximately 93% was attained by the use of 19,000 m3 of snow stored from the winter. The majority of the snow/ice was natural while the rest was artificially made with snowguns and a hose. The snow was stored in a 140×60-m shallow pond of watertight asphalt. A 0.2-m layer of wood chips thermally insulated the snow. The operation of the plant experienced only minor problems. Luleå University of Technology is responsible for the scientific evaluation of the project. This paper compiles the results and experiences of the snow cooling plant during the first year of operation in 2000.

  • 19.
    Skogsberg, Kjell
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Wood chips as thermal insulation of snow2005In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 43, no 3, p. 207-218Article in journal (Refereed)
    Abstract [en]

    Snow (and ice) cooling is in some areas an alternative cooling technique to chillers. However, to utilise snow cooling during the summer, storage is needed. Snow storages were traditionally insulated by sawdust. A large demonstration plant has been in operation since 2000 for cooling the regional hospital in Sundsvall, Sweden. This storage is thermally insulated by larger wood chips. This paper summarizes laboratory testing of some key factors that influence the functioning of cutter shavings (another kind of wood chips) as thermal insulation. The melt rate significantly increased with increased wind velocity, light intensity (from spotlight bulbs), air temperature, and air humidity. A 1 cm thicker layer of cutter shavings decreased the melt rate about 0.097 kg m- 2 h- 1, within the studied layer limits of 2.5 to 7.5 cm. The melt rate with initially wet cutter shavings was about the same as for initially dry cutter shavings. This was explained by the increased evaporation which balanced increased thermal conductivity. Evaporation was found to be an important part of the energy balance and reduced the melt rate. Solar light reflectivity of new cutter shavings was measured in a separate outdoor experiment, found to be about 20%.

  • 20.
    Skogsberg, Kjell
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    The Sundsvall hospital snow storage2001In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 32, no 1, p. 63-70Article in journal (Refereed)
    Abstract [en]

    During the summer, the regional hospital in Sundsvall in central Sweden requires 1000 MW h of cooling with a maximum cooling power 1500 kW. From the summer of 2000, seasonally stored snow will be utilised to meet the cooling demand. A storage area of 140×60 m with a capacity for 60,000 m3 (40,000 tons) of snow was constructed in 1999. Initially, about half of this volume will be stored. The storage consists of a shallow pit made of watertight asphalt. A layer of wood chips covering the snow reduces the natural melting to 20–30% of the total volume. Meltwater from the snow storage is pumped to the hospital. After cooling the hospital, the heated meltwater is re-circulated to the snow storage. When all the snow has melted, the wood chips will be burnt in a local heating plant. Luleå University of Technology is responsible for the scientific evaluation of the project. This paper describes the construction and the simulated operation of the snow storage system.

  • 21.
    Sundström, Nils
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kruglyak, Andrey
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Friborg, Johan
    Malå GeoScience AB.
    Modeling and simulation of GPR wave propagation through wet snowpacks: testing the sensitivity of a method for snow water equivalent estimation2012In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 74-75, p. 11-20Article in journal (Refereed)
    Abstract [en]

    Snow water equivalent (SWE) of a snowpack is an important input to the distributed snow hydrological models used for runoff predictions in areas with annual snowpacks. Since the conventional method of manually measuring SWE is very time-consuming, more automated methods are being adopted, such as using ground penetrating radar operated from a snowmobile with SWE estimated from radar wave two-way travel time. However, this method suffers from significant errors when liquid water is present in the snow.In our previous work, a new method for estimating SWE of wet snowpacks from radar wave travel times and amplitudes was proposed, with both these parameters obtained from a common mid-point survey. Here we present a custom ray-based model of radar wave propagation through wet snowpacks and results of MATLAB simulations conducted to investigate the method's sensitivity to measurement errors and snowpack properties. In particular, for a single-layer snowpack up to 2.1 m deep and with liquid water content up to 4.5% (by volume), the simulations indicate that SWE can be estimated with an error of ± 5% or less if (a) the noise (measurement errors) in the resulting amplitude has a standard deviation less than 15% and(b) the noise in two-way travel time has a standard deviation less than 0.075 ns (22.5% and 0.15 ns for a snowpack less than 1.3 m deep).

  • 22.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laboratory study of stone heave in till exposed to freezing and thawing1998In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 27, no 2, p. 141-152Article in journal (Refereed)
    Abstract [en]

    Cyclic freezing and thawing of soils affect the structure and might, under certain conditions, cause stones and particles to move and relocate. The movement of stones will influence the soil structure and create weak and loose parts with increased permeability. This phenomenon has been known for a long time, but the knowledge regarding the magnitude of stone heave and soil conditions necessary for heave to take place has been lacking. Therefore, laboratory tests were carried out. Fine-grained till (moraine) was compacted to different void ratios and then saturated in a rigid wall permeameter which was exposed to one-dimensional freezing and thawing in a closed water system. The movements of an embedded stone were measured by an X-ray technique. Unfrozen samples, as well as samples frozen and thawed, were X-rayed and the stone movements were quantified after 1, 2, 4, and 10 cycles of freezing and thawing. The results show that stone movements (vertical and horizontal) take place due to freeze/thaw. The void ratio (the ratio of the volume of void space to the volume of solid substance in the sample) was found to be a key parameter for whether upward or downward stone movements took place. The downward movement occurred when the soil had a high void ratio, and the upward when the void ratio was small. In the loose soil, the stone first moved downwards and then, when the soil became denser due to freeze/thaw, it changed direction and heaved. In the loose soil, significant movements in the horizontal direction as well as rotation of the stone were also found.

  • 23.
    Viklander, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Eigenbrod, Dieter
    Lakehead University, Thunder Bay, Ontario.
    Stone movements and permeability changes in till caused by freezing and thawing2000In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 31, no 2, p. 151-162Article in journal (Refereed)
    Abstract [en]

    Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured. Vertical uplifting of boulders and stones is well known to take place in cold regions. Movements of stones in roads might lead to traffic danger, vehicle failures, and cause breakdown of the road surface with the need of expensive repair as a consequence. In addition, freeze/thaw and associated stone movements may cause an increase in permeability, which can lead to contamination of soils and ground water if used as soil liners in landfill areas or even dam failures if used as hydraulic barriers in earth dams. Freeze/thaw tests were carried out in the laboratory on a silty sandy soil in order to study movements of embedded stones and to measure how the overall permeability was influenced by freeze/thaw cycles. The soil samples were compacted at three different water contents, i.e. 11.5% (optimum), 14.5%, and 17.5%. Each sample contained one stone, placed at a predetermined depth. The soil samples were subjected to one-dimensional open system freeze/thaw. Soil temperatures, volume changes, and stone movements were measured. The results showed that upward stone movements took place due to freeze/thaw in the frost susceptible soil compacted at and 3% above the optimum water content. In addition, the permeability increased in samples with initial water contents of 11.5% and 14.5%. This permeability increase was as much as 81 times after six freeze/thaw cycles. For the samples with initial water contents of 17.5%, very small changes in permeability were measured.

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