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  • 301.
    Ormann, Linda
    et al.
    Geotechnical Engineer, SWECO Infrastructure AB, Gjörwellsgatan 22, Stockholm.
    Zardari, Muhammad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mattsson, Hans
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Bjelkevik, Annika
    Geotechnical Engineer, SWECO Infrastructure AB, Gjörwellsgatan 22, Stockholm.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Numerical analysis of curved embankment of an upstream tailings dam2011Inngår i: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 16, nr I, s. 931-944Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 302.
    Osman, Yasin
    et al.
    University of Bolton.
    Abdellatif, Mawada
    Liverpool JM University.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Jawad, Sadeq
    Iraqi Government, Prime Minister Advisory Commission.
    Climate Change and Future Precipitation in Arid Environment of Middle East: Case study of Iraq2017Inngår i: Journal of Environmental Hydrology, ISSN 1058-3912, E-ISSN 1996-7918, Vol. 25, s. 1-18, artikkel-id 3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper impact of climate change on precipitation in the arid environment of Iraq is examined.  LARS-WG weather generator was applied to 5 representative regions to model current and future precipitation under climate change. Seven Global Climate Models (GCMs) have been employed to account for any uncertainty on future projection for three selected periods, 2011-2030, 2046-2065 and 2080-2099. Performance of LARS-WG in each site was first evaluated using the Kolmogorov-Smirnov statistical test for fitting wet/dry days in each site, as well as comparison of the mean and standard deviation between the observed and simulated precipitation. The developed LARS-WG models were found to perform well and skilful in simulating precipitation in the arid regions of Iraq as evidenced by the tests carried and the comparison made. The precipitation models were then used to obtain future projections for precipitation using the IPCC scenario SRES A2. Future precipitation results show that most of the Iraq regions are projected to suffer a reduction in annual mean precipitation, especially by the end of the 21st century, while on a seasonal basis most of the regions are anticipated to be wetter in autumn and winter.

     

  • 303. Osman, Yassin
    et al.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Adbellatif, Mawada
    Al-Jawad, Sadeq
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Expected Future Precipitation in Central Iraq Using LARS-WG Stochastic Weather Generator2014Inngår i: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 6, nr 13, s. 948-959Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Middle East (ME) is characterized by its water shortage problem. This region with its arid climate is expected to be the most vulnerable in the world to the potential impacts of climate change. Iraq (located in ME) is seriously experiencing water shortage problem. To overcome this problem rain water harvesting can be used. In this study the applicability of the long-term weather generator model in downscaling daily precipitation Central Iraq is used to project future changes of precipitation based on scenario of seven General Circulation Models (GCMs) outputs for the periods of 2011-2030, 2046-2065, and 2080-2099. The results indicated that December-February and September-November periods, based on the ensemble mean of seven GCMs, showed an increasing trend in the periods considered; however, a decreasing trend can be found in March, April, and May in the future.

  • 304.
    Pousette, Kerstin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Eriksson, Lars
    MRM Konsult AB.
    Knutsson, Sven
    Acidification properties of sulphide soil: a classification system based on leaching tests2008Inngår i: NGM 2008: Nordisk Geoteknikermøte i Sandefjord 4.- 6. september 2008 / [ed] Kaare Flate; Tor-Erik Frydenlund; Jon Prestegarden; Kåre Senneset, Norsk Geoteknisk Forening , 2008, s. 415-422Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The acidification effect from excavated sulphide soil is an environmental problem. In a project financed by the Swedish Road and Railway Administrations, a handbook was written on the best practice for managing sulphide soil masses to avoid this problem. A classification system for the acidification properties of sulphide soils, based on results from a leaching method developed by MRM Konsult AB, are proposed in the handbook. Results from over 100 leaching tests have been evaluated where the influence of different parameters has been studied.

  • 305.
    Pousette, Kerstin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Klassificering av sulfidjord med hänsyn till miljö och teknik2007Inngår i: Bygg & Teknik, ISSN 0281-658X, Vol. 99, nr 1, s. 40-44Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 306.
    Pousette, Kerstin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Study of a sulfide soil deposit at a road construction in Sunderbyn, near Luleå in the north of Sweden2012Inngår i: 7th International Acid Sulfate Soil Conference in Vaasa, Finland 2012, Proceedings volume: Towards Harmony between Land Use and the Environment / [ed] Peter Österholm; Markko Yli-Halla; Peter Edén, Geological Survey of Finland , 2012, s. 86-87Konferansepaper (Fagfellevurdert)
  • 307.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Börgesson, Lennart
    Clay Technology, AB.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Origin of silty fracture fillings in crystalline bedrock1990Inngår i: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 112, nr 3, s. 209-213Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Silty fillings in subhorizontal fractures of large area are occasionally found at shallow depth in Swedish bedrock. The soil was deposited after widening of the fractures due to the rock stress conditions at the edge of retreating ice sheets, a probable further implication being artesian conditions leading to hydraulic lifting. It is concluded that if the rate of ice retreat was sufficiently high, the basal part of the ice would be adfrozen to still frozen rock, and highly pressurized meltwater discharged through interconnected, steep and flat-lying fractures, which became filled with soil material transported with the water.

  • 308.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Kasbohm, Jörn
    Greifswald University.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Roles of clay and concrete in isolating high-level radioactive waste in very long holes2013Inngår i: International Journal of Research and Reviews in Applied Sciences, ISSN 2076-734X, E-ISSN 2076-7366, Vol. 16, nr 2, s. 263-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Groundwater flow transports possibly released radionuclides from underground repositories to the biosphere. It can also make construction difficult as is obvious from examining technical solutions for disposal of high-level radioactive waste (HLW) in long subhorizontally bored holes (KBS-3H) and in very deep boreholes (VDH). The presence of intersected, water-bearing fracture zones requires concrete for sealing these parts of the holes while the rest contains canisters surrounded and separated by dense, expandable clay. Casting of the concrete should be preceded by grouting of the fractured rock using cementitious materials composed so that mutual physical and chemical interaction do not degrade either of them. For the sake of rock stability the horizontal holes have to be located at very moderate depth, 400-500 m, where the rock has a high average hydraulic conductivity, while the slimmer, steep holes reaching down to 4 km are kept stable by using clay mud in the construction phase and dense clay for long term performance. The rock at this depth is much less permeable than higher up and the groundwater sufficiently salt to be maintained there, causing only local thermally induced circulation of possibly contaminated water. The KBS-3H concept involves practical difficulties and risks in the installation of the clay seals and waste canisters, for which the risk of shearing by slip of frequently intersected steep fractures is a major threat after closure of the repository. The VDH concept relies on effective sealing of the upper part of the deep holes and puts less demand on the seals in the lower, waste-bearing part, for which the buoyancy conditions of the groundwater make it a major barrier to upward migration of possibly released radionuclides.

  • 309.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    VDH – a case of ostrich philosophy or a serious alternative for the disposal of highly radioactive waste?2014Inngår i: Waste Management and the Environment VII / [ed] C.A. Brebbia; G. Passerini; H. Itoh, Southampton: WIT Press, 2014, s. 377-390Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Two basically different concepts for disposal of highly radioactive waste are the often cited KBS-3 method implying isolation of such waste in copper canisters in short holes bored from tunnels at a depth of a few hundred meters, and disposal in the lower part of 4 km deep holes (VDH). The deep hole concept has the advantage that the waste packages will be located in very salt, stagnant groundwater in rock that is much less permeable than shallow rock with repositories of KBS-3V type. Disadvantages are that some of the techniques for installation have not yet been demonstrated and that retrieval of damaged or stuck canisters is deemed more difficult than for KBS-3V. Both concepts require precise adaption of canister and seal positions to the rock structure, which, for KBS-3 repositories, is not known until the tunnels have been constructed. For VDH, pilot borings provide such knowledge at low cost at a very early stage. The deep holes need to be supported by casings and all work deeper than 500 m must be made with clay mud in them. Reconsideration of the design and function of VDH shows that it has significant advantages, primarily respecting cost and construction time, and that new types of concrete for sealing purposes can make such repositories safer than KBS-3V disposal since seismic and tectonic events are less detrimental and future glaciations will cause much less disturbance. The most important value is that the groundwater that can possibly become contaminated by failing engineered barriers will stay at more than 2000 m depth and that there is no mechanism that can bring it up to the biosphere

  • 310.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kasbohm, Jörn
    Institute of Geography and Geology, Ernst-Moritz-Arndt-University of Greifswald, University of Greifswald, GeoENcon Ltd.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Comparison of two genuinely geological alternatives for disposal of highly radioactive waste (HLW)2016Inngår i: Comunicações Geológicas, ISSN 0873-948X, E-ISSN 1647-581XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Disposal of highly radioactive waste (HLW) can be environmentally acceptable if radionuclides are kept isolated from the groundwater, which has inspired planners of repositories to work out multibarrier concepts that postulate defined functions of the host rock and engineered waste confinements. Assessment of the role of the host rock involves groundwater flow modelling and rock mechanical analysis, which are both highly speculative and ignore future changes in rock structure, stress conditions, and groundwater flow. Widening the perspective by considering the integrated physical performance of interacting geological strata respecting groundwater flow conditions can provide excellent isolation of HLW with a minimum of engineered barriers as illustrated by the principle of very deep boreholes (VDH) for which the very high salt content of deep water is the primary barrier by maintaining possibly contaminated groundwater at depth. Such isolation of groundwater regimes can also be obtained by constructing repositories in crystalline rock covered by clay-containing sedimentary rock in regions with no or very low hydraulic gradients, particularly if the two principles are combined. The paper describes a possible case of this type, showing that effective isolation of HLW in repositories of commonly discussed types, KBS-3H and VDH, can be achieved under present and foreseeable climatic conditions. The paper compares the short- and long-term functions of repositories located at the southern end of the Swedish island Gotland, being an example of desired geological conditions that are found also in other parts of Sweden and in Lithuania, Germany, Holland and the UK. Here, 500 m of sediment rock series cover gneiss bedrock in which a KBS-3H repository of SKB-type can be built under virtually “dry” conditions because of the tightness of the overlying sedimentary rock and lack of hydraulic gradients in the crystalline rock. Shafts leading down from the ground surface to the repository level are constructed by use of freezing technique and lined with low-pH concrete before installation of waste after which they have to be sealed with expanding clay. Use of initially largely water-saturated clay provides suitable physical properties of the embedment of waste containers. Alternatively, a VDH repository consisting of a number of steep 4 km deep boreholes with about 800 mm diameter can be driven for installing waste below 2 km depth, leaving the upper 2 km for sealing with clay. The geological conditions, which are also believed to provide acceptable rock pressure conditions for construction of a KBS-3H repository at about 600 m depth, are believed to be suitable for the construction and short- and long-term performance of either repository type.

  • 311.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kasbohm, Jörn
    GeoENconLtd, Institute of Geography and Geology, Univ. of Greifswald, Germany.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Two genuinely geological alternatives for disposal of highly radioactive waste (HLW)2016Inngår i: Communicacaoes Geologicas, ISSN 0873-948X, Vol. 103, s. 25-39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Disposal of highly radioactive waste (HLW) can be environmentally acceptable if radionuclides are kept isolated from the groundwater, which has inspired planners of repositories to work out multibarrier concepts that postulate defined functions of the host rock and engineered waste confinements. Assessment of the role of the host rock involves groundwater flow modelling and rock mechanical analysis, which are both highly speculative and ignore future changes in rock structure, stress conditions, and groundwater flow. Widening the perspective by considering the integrated physical performance of contacting geological strata respecting groundwater flow conditions can provide excellent isolation of HLW with a minimum of engineered barriers as illustrated by the principle of very deep boreholes (VDH) for which the very high salt content of deep water is the primary barrier by maintaining possibly contaminated groundwater at depth. Such isolation of groundwater regimes can also be obtained by constructing relatively shallow repositories in crystalline rock covered by clay-containing sedimentary rock in regions with no or very low hydraulic gradients. The paper describes a possible case of this type, showing that effective isolation of HLW in repositories of commonly discussed types, KBS-3H and VDH, can be achieved under present climatic conditions.

    The paper compares the short- and long-term functions of repositories located at the southern end of the Swedish island Gotland, being an example of desired geological conditions that are found also in other parts of Sweden and in Lithuania, Germany, Holland and the UK. Here, 500 m of sediment rock series cover gneiss bedrock in which a KBS-3H repository of SKB-type can be built under virtually “dry” conditions because of the tightness of the overlying sedimentary rock and lack of hydraulic gradients in the crystalline rock. Shafts leading down from the ground surface to the repository level are constructed by use of freezing technique and lined with low-pH concrete before installation of waste after which they have to be sealed with expanding clay. Use of initially largely water-saturated clay provides suitable physical properties of the embedment of waste containers. Alternatively, a VDH repository consisting of a number of steep 4 km deep boreholes with about 8oo mm diameter can be driven for installing waste below 2 km depth, leaving the upper 2 km for sealing with clay. The geological conditions, which are also believed to provide acceptable rock pressure conditions for construction of a KBS-3H repository at about 600 m depth, are believed to be suitable for the construction and short- and long-term performance of either repository type. 

  • 312.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kasbohm, Jörn
    Greifswald University, Germany .
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hoang-Minh, Thao
    Greifswald University, Germany .
    Nguyen-Thanh, Lan
    Technical University of Darmstadt, Germany.
    Disposal of Low- and Intermediate-Level Radioactive Waste2019Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 9, nr 3, s. 237-272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As for isolation of high-level radioactive waste by use of smectite clay it serves very well also for hindering radionuclides from low- and intermediate-level waste to contaminate groundwater. It can be used for minimizing groundwater flow through and along waste packages and for providing them with ductile embedment for eliminating the risk of damage caused by displacements in host rock or concrete vaults. The clay can have the form of liners placed and compacted on site over vaults constructed on the ground surface, or consist of compacted blocks of clay granules that are tightly placed around waste packages in underground drifts and rooms. In either case the initially incompletely water saturated clay will swell in conjunction with water uptake until tight contact with the confining medium has been established. The clay seals must be sufficiently dense to fulfill criteria set with respect to hydraulic conductivity and swelling capacity, paying due attention to the salt content in the porewater. Their physical and chemical stabilities must be acceptable in short- and long-term perspectives, which is a few hundred years for most low-level wastes up to tens of thousands of years for long-lived waste. 

  • 313.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kasbohm, Jörn
    Greifswald University.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Nguyen-Thanh, Lan
    Technical University of Darmstadt.
    The role of smectite clay barriers for isolating high-level radioactive waste (HLW) in shallow and deep repositories2015Inngår i: Vol. 15, s. 680-687Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The major engineered barriers to migration of radionuclides from HLW in repositories are the canister and surrounding smectite clay. They interact physically and chemically by which the properties of both are changed, especially of the smectite “buffer” clay that is examined in the paper. The canisters are made of copper-lined iron according to the Swedish and Finnish concepts, steel being an alternative. The function of the host rock is of importance and the paper examines the role of two repository concepts with long subhorizontal or deep vertical holes for placing the waste. The hydraulic conductivity of the canister-embedding smectite clay can be significantly raised by high temperature and temperature gradients, which generate precipitation of salt and silica in different parts of the buffer clay. The impact of the degrading processes on the waste-isolating capacity is different for shallow repositories in permeable rock and for very deep disposal with higher temperature. The latter has stagnant groundwater as major barrier to the migration of radionuclides.

  • 314.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Kasbohm, Jörn
    Greifswald University.
    Thao, Hoang- Minh
    Hanoi University of Science, Vietnam National University.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Thanh, Lan Ngyuen
    Technical University of Darmstadt.
    Holmehus clay: A Tertiary smectitic clay of potential use for isolation of hazardous waste2015Inngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 188, s. 38-47Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Danish Tertiary Holmehus clay belongs to the series of illite-smectite mixed-layer clays in northern Europe and has a potential to serve as an effective engineered barrier for isolating hazardous waste. Mineralogical specification was made of the components illite/smectite mixed-layer and dioctahedral vermiculite/smectite mixed-layer structures. The lower content of expandable phase than of smectite- rich clays like MX-80 gives somewhat higher hydraulic conductivity and somewhat lower swelling pressure but both are deemed suitable for isolating canisters with high-level radioactive waste in deeprepositories for densities at water saturation of at least 1900 kg/m3. The lower swelling pressure, the potential of being chemically more stable, and the high buffer capacity by providing dissolved Si makes Holmehus clay a candidate for use in both deep and near-surface repositories.

  • 315.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Flow and ductility of smectitic clay for skin treatment2014Inngår i: Journal of Cosmetics, Dermatological Sciences and Applications, ISSN 2161-4105, E-ISSN 2161-4512, Vol. 4, s. 67-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is important that pastes and creames for skin treatment have suitable rheological properties and ability to establish good contact with the tissues while retaining their tightness. Thixotropy is desired for providing fluidity when agitated and a suitably degree of stiffening thereafter. This requires low shear resistance in the coating phase and microstructural reorganization when leaving the paste to rest. Following the principle of using only mineral components for skin treatment use of expandable hydrophilic clay minerals should be considered. They sorb cations and positively charged organic molecules and are impermeable to fluids and gas under low pressure, hence providing oxygen-free micro-environment. They can balance pH and are excellent agents for cleaning skin.

  • 316.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Taie, Laith
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    The impact of hydraulic gradients and boundary conditions on the microstructural stability of clayey backfills with special respect to the risk of piping and erosion2012Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 2, nr 1, s. 89-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Disposal of hazardous waste like high-level radioactive waste (HLW) is made by confining it in canisters surrounded by dense, ductile “buffer” clay for placement in deposition holes at a few hundred meters depth in crystalline rock. The concept favoured by authorities in Sweden, Finland and Canada implies that the holes are bored from blasted or bored tunnels to be tightly backfilled by stacking compacted blocks of clay in the center and filling the remaining space between the blocks and the rock with blown-in clay pellets. The problem with this is that water flowing in from the rock can cause piping and erosion of the pellet filling, which can turn it into mud and disturb the placement of canisters and buffer clay. The controlling parameter is the rate of inflow of water per inflow point, which is determined by the structure and hydraulic conductivity of the rock. The paper describes a simple model of the mechanisms in penetration of water into the pellet fill and provides a basis for estimating the required rate of backfilling for avoiding critical conditions. The study indicates that such conditions will be caused irrespective of the rate of water inflow per point if the backfilling rate is low.

  • 317.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Taie, Laith
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Optimal ways of disposal of highly radioactive waste2012Inngår i: Natural Science, ISSN 2150-4091, E-ISSN 2150-4105, Vol. 4, nr 11A, s. 906-918Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multibarrier concepts are commonly proposed for effective isolation of highly radioactive waste (HLW). Present concepts consider the host rock as a barrier by retarding migration of possibly released radionuclides to the biosphere, containers for preventing release of radionuclides, and “buffer clay” embedding the canisters for providing ductility and minimizing the risk of container breakage and for delaying migration of possibly escaping radionuclides. Closer analysis of the isolating functions shows that rock will only serve as a mechanical protection of the “nearfield”, the containers of proposed types can be short-lived, and the surrounding clay will be increasingly permeable and stiffen hence becoming less ductile with time. A different approach, representing an alternative to the common concepts, can be safer and cheaper. It takes the HIPOW copper canister as the only major barrier and a cheap but sufficiently efficient buffer as embedment. The repository can consist of an abandoned copper mine, an option being to place HLW in emptied drifts while mining is still going in not yet exploited parts of the ore body.

  • 318.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Taie, Laith
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Shahrestanakizadeh, Mehras
    Luleå University of Technology.
    Isolation of hazardous soil contaminated by DU (depleted uranium) from groundwater2012Inngår i: Waste Management and the Environment VI / [ed] V. Popov; H. Itoh; C.A. Brebbia, WIT Press, 2012, s. 297-308Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cappings of waste piles conventionally contain a drain layer over a low-permeable clay liner composed of smectite minerals. The rate of percolation of the clay liner, once it has been largely water saturated, determines the downward migration of water into and through the underlying waste. In desert climate, cyclic variation in the degree of hydration of the clay takes place, from desiccated to largely water saturated conditions. Clays of smectite type effectively seal off the underlying waste but the content must be low for preventing contraction and expansion causing a reduced isolation potential of the liner. Penetration of the liner, implying wetting of the waste, starts when the top liner is largely water saturated but the hydration followed by dehydration is confined to take place only to a limited depth according to the assumed wetting mechanism. The rate of wetting usually follows a log time law. For an ideal composition and density of the upper clay liner there will be no percolation and wetting of the underlying waste. The paper is focused on the mechanisms involved in hydration/dehydration of top clay liner prepared by mixing clay and ballast material for providing a basis for design, construction and maintenance of well performing cappings.

  • 319.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Isolation of hazardous waste in crystalline rock2012Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 2, nr 3, s. 57-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radioactive waste from the nuclear industry and hazardous products from chemical industries need to be effectively isolated from the biosphere for a very long time. Highly radioactive waste gives off heat and requires disposal at depth in special repositories while low-level radioactive waste, pesticides and mercury and arsenic, can be stored in deep mines. The multiple barrier principle implies that the rock and engineered barriers combine to provide isolation but assessment of the constitution and performance of crystalline rock reduces its role to provide “mechanical support” to waste containers rather than true isolation of them. Smectitic clay is required for achieving this but its isolating capacity is limited over time, and long-lasting waste containers are needed as well. The waste isolation effect of clay and containers can allow for constructing repositories in rock of rather poor quality, represented by abandoned mines, and waste containers of 100 % copper further reduce the need for very well planned and constructed repositories.

  • 320.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    El-Tekno AB.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Pourbakhtiar, Alireza
    Can sealing of rock hosting a repository for highly radioactive waste be relied on?2012Inngår i: Natural Science, ISSN 2150-4091, E-ISSN 2150-4105, Vol. 4, nr 11A, s. 895-905Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multibarrier systems are commonly proposed for effective isolation of highly radioactive waste (HLW). Presently considered concepts take the host rock as a barrier claiming it to retard migration of possibly released radionuclides from HLW containers to the biosphere. This capacity is small unless water-bearing fracture zones intersecting the blasted waste-containing tunnels and excavation-disturbance zones around them can be sealed by grouting and construction of bulkheads, but this is effective only for a very limited period of time as explained in the paper. The disturbed zones thence make the entire repository serve as a continuous hydraulic conductor causing quick transport of released radionuclides up to the biosphere. The dilemma can be solved by accepting the short-circuiting function of the disturbed zones along the tunnels on the condition that totally tight waste containers be used. Deep holes bored in the site selection phase through the forthcoming repository can be effective pathways for radionuclides unless they are properly sealed. They are small-scale equivalents of tunnels but do not have any ex-cavation damage and can be effectively sealed by using clay and concrete of new types. Applying this principle to very deep boreholes with a diameter of a few decimeters would make it possible to safely store slim, tight HLW canisters for any period of time.

  • 321.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Xiaodong, Liu
    East China Institute of Technology, Fuzhou, Jiangxi.
    Prikryl, Richard
    Charles University, Prague.
    Numerical calculation of the rate and distribution of porewater flow in clay used for isolating hazardous waste2011Inngår i: Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing / [ed] Barry H. V. Topping; Y. Tsompanakis, Kippen, Stirlingshire: Civil-Comp Press , 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The hydraulic performance of clay barriers for isolating hazardous waste products depends on the experimentally determined hydraulic conductivity. While the large majority of a cross section of dense smectite clay is nearly impermeable because of the immobility of the sorbed porewater, there are narrow, tortuous channels that are more or less continuous. They contain less dense clay gels that let water through under hydraulic gradients. Applying the 3Dchan code one finds fair agreement between theoretical and experimental hydraulic conductivities for smectite-rich clay if hydraulic gradients of 30-50 are used, while flow experiments using very high gradients give much lower conductivities. The discrepancy can be explained by the high flow rate in the channels by which particles are moved, causing clogging. The process is illustrated by using FEM analysis of the flow rate distribution and by applying Computational Fluid Dynamics (CFD).

  • 322.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Xiaodong, Liu
    East China Institute of Technology, Fuzhou, Jiangxi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Creep can strengthen clay: a matter of long-term slope stability2016Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, nr 1, s. 1-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The matter of long-term stability of long, natural slopes in illitic clay is of great practical importance in Scandinavia and Canada and has been frequently discussed among geotechnical specialists. A remaining question is how such natural slopes can have remained stable, yet undergoing large strain, for hundreds and thousands of years, during which critical conditions have repeatedly occurred with calculated safety factors lower than or equal to unity according to common stability calculations based on plastic theory. The reason for this may be the role of creep shear strain that causes redistribution of stress and earth pressure leading to a state of equilibrium that is very sensitive to disturbance and represents a condition of near-failure. Triggering of occasional slides can be explained by temporary high porewater pressure caused by periods of intense rain, disturbance by pile driving, or loading by road construction etc, taken place in slopes that have been stable for very long periods of time. The mechanisms by which creep can lead to stable conditions of very old clay slopes can have the form of successive relative particle movements into a state where the interparticle bonds become stronger but of brittle character, according to a model based on stochastical mechanics.

  • 323.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mohammed, Mohammed H.
    Department of Civil Engineering University of Mosul.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    Eltekno AB, Oscarshamn, Sweden.
    Liw, Lars
    Lars Liw Company.
    Fracking - Prevention of leakage of oil and gas from abandoned holes in consolidated rock2016Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, nr 1, s. 19-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fracking of deep shales is used in the US for making otherwise unavailable gas and oil in dense rock exploitable but can cause problems by leakage to the ground surface or shallow aquifers of such matter and of water contaminated by chemicals used for release of the precious substances. The issue is primarily boring disturbance causing a high-permeable annulus around boreholes that interacts hydrologically with natural fracture zones, and secondarily, malfunctioning concrete liners. A novel approach for new holes is to eliminate leakage by constructing long-lasting linings, and chemically stable concrete plugs where permeable fracture zones are intersected. The vertical parts of abandoned holes can be sealed by construction of concrete plugs where such zones are intersected and by installing clay seals in between. For holes to be abandoned, long-term sealing is provided by installing very dense smectitic clay plugs that are chemically compatible with the concrete.

  • 324.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Popov, Viktor
    Ascend Technologies Ltd, Southampton, UK.
    Adey, Robert
    C M BEASY Ltd, UK.
    Kasbohm, Jörn
    University of Greifswald.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Rational and Economic Disposal of Hazardous Waste: Use of Abandoned Mines2014Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 4, nr 2, s. 33-54Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep geological disposal of dangerous waste like mercury, solidified organic pesticides and radioactive rest products, requires suitable engineered barriers. Use of deep abandoned mines is a rational and economic alternative to construction of a repository in virgin rock but requires knowledge of the structural constitution of the rock for assessment of groundwater flow and rock mechanical conditions. Such information is much more detailed through the activities of mining companies than from exploration of virgin rock. Organizations responsible for disposal of radioactive waste in crystalline rock count on the host rock as a barrier to migration of released radionuclides to the biosphere but present investigations reduce its role to provide mechanical support of the waste packages while effective hindrance of migration of contaminants can be offered by engineered barriers, i.e. waste containers and clay embedding them. For certain waste in granular form, like Hg batteries, mixing with expandable clay and layerwise placement and compaction is deemed possible as described in the paper. The primary role of the clay is to make the clay-mixed waste very tight and ductile. By constructing liners of highly compacted clay blocks along the periphery of the disposal rooms the rock is given sufficient support and effective isolation of the waste. If the liners have a thickness of 0.5-1 m and placed in dry form the time for complete water saturation of the clay/waste mixture can be several thousands of years. Not until then migration of hazardous waste elements to the rock can start.A major role in the hydrological performance of the host rock is that of the excavation-disturbed zone (EDZ). It short-circuits the natural system of flow paths and causes quick transport of released contaminants to downstream wells

  • 325.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Prikryl, Richard
    Institute of Geochemistry, Charles University, Prague.
    Weishauptová, Zuzana
    Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, Prague.
    Xiaodong, Liu
    East China Institute of Technology, Fuzhou, Jiangxi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Role of clay microstructure in expandable buffer clay2012Inngår i: Journal of Purity, Utility Reaction and Environment, ISSN 2232-1179, Vol. 1, nr 6, s. 267-292Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Smectite-rich clay is a major engineered barrier (buffer) in repositories for heat-producing highly radioactive waste. It has the form of densely compacted blocks of clay granules and is only partly water saturated from start. The initial porewater is redistributed by the thermal gradient acting in the buffer and additional water is taken up to give ultimately complete saturation. The compaction of blocks gives a stochastic distribution of dense and less dense clay grains of different size and the initially heterogeneous microstructure is partly preserved in the fully hydrated buffer. Thus, local softer zones combine to create channel flow under hydraulic gradients and they can be permanent by precipitation of cementing agents caused by salt in the porewater and by partial dissolution of the smectite particles. A fundamental question is how one can characterize the channels and quantify their hydraulic performance. This has been answered by using different techniques in the present study, including optical and electron-optical microscopy and gas adsorption. Interpretation of oedometer tests with freshly prepared and hydrothermally treated smectite samples has revealed that permeation of dense buffer clay primarily takes place through a network of channels that represent up a few percent of the entire cross section. Hydrothermal treatment in the early period of maturation of the buffer widens flow paths and increase the bulk conductivity, and precipitation of cementing silicious compounds causes stiffening and prevents expanded voids to close.

  • 326.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    D ElTekno AB.
    Kasbohm, Jörn
    GeoENcon Ltd.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    The concept of highly radioactive waste (HLW) disposal in very deep boreholes in a new perspective2012Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 2, nr 3, s. 1-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two basically different concepts for disposal of highly radioactive waste are the often cited KBS-3 method and a concept termed VDH (Very Deep Boreholes). So far, the deep hole concept has been ranked as number two because the canisters are not assumed to be retrievable and because some of the techniques for installation of the waste are not yet at hand. Reconsideration of the design and function of VDH shows that, in addition to the advantage of no transport of released radionuclides by groundwater flow up to the ground level because of the almost stagnant salt groundwater at depth, the rock at depth is considerably less permeable than for mined repositories at shallow depth. A further advantage is that VDH will be less affected by future glaciations. Less good is that precise adaption of canister and seal positions to the rock structure cannot be made until boring of the deep holes is complete. Furthermore, the deep holes need to be supported by casings and all work deeper than 500 m must be made with mud in them. Retrieval of damaged casings and stuck canisters may be more difficult than in mined repositories.

  • 327.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    El-Tekno AB, Eltekno AB, Oscarshamn, Sweden.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Modern method for sealing deep boreholes2016Inngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 202, s. 132-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for sealing cored boreholes using dense montmorillonite clay in perforated copper tubes where the rock has only very fine fractures, and concrete cast where the holes intersect water-bearing fracture zones, has been used for closing 100 to 500 m deep boreholes made for site investigation in Sweden and Finland. Application of this technique to even deeper boreholes requires performance analysis respecting placeability and long-term function of the clay and concrete, individually and in combination, as discussed in the paper. Placeability requires that maturation of the initially unsaturated clay is neither too fast nor too slow and means of controlling the rate are described. The proposed concrete material has a very low cement content and talc as fluidizer, which gives slow but ultimately very significant strengthening and low solubility of the cement reaction products. At a few kilometers depth the temperature can be more than 60oC, which has to be sustained by the sealing materials, and this makes saponite and mixed-layer smectite/illite possible alternatives to montmorillonite clay. The concept is judged to be applicable also to backfilling of wider holes for disposal of highly radioactive waste.

  • 328.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    El-Tekno AB.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Predicted and actual wetting rate of buffer in repositories for high-level radioactive waste2014Inngår i: Waste Management and The Environment VII / [ed] C.A. Brebbia; G. Passerini; H. Itoh, Southampton: WIT Press, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Underground test sites for disposal of high-level radioactive waste (HLW) are commonly equipped with instrumentation for documentation of the evolution of engineered barriers and of changes in the physical state of the host rock. The rate of hydration of the clay buffer surrounding waste canisters determines the physical interaction with the rock and waste canisters and is recorded by use of RH meters and by measuring the swelling pressure exerted on cells installed in the clay. They are connected to cables and tubings extending to the recording units placed in room atmosphere. If they pass from the rock through the buffer groundwater under pressure can migrate through or along bunches of cables and tubings and reach the points of measurement earlier than in clay without instrumentation. The inconvenience is avoided by tight embedment of individual cables and tubings and placement of the pressure gauges such that they do not pass through the clay. Incorrect rates of hydration has led to the inadequate conclusion that water flows in unsaturated parts of the buffer according Darcy’s law while it is in fact migrating by coupled diffusion processes.

  • 329.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    Eltekno AB, Oscarshamn, Sweden.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Medium-deep or very deep disposal of highly radioactive waste?2013Inngår i: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 7, nr 12, s. 1548-1565Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several of the commonly proposed concepts for disposal of highly radioactive waste (HLW) imply construction at medium depth (400-600 m) in granitic rock, which is excellent for constructing a stable repository since it provides effective mechanical protection of the waste. A drawback is that major water-bearing fracture zones are frequent and must be avoided in the site selection process since they can undergo large deformations caused by seismic and tectonic events and cause failure of waste containers located in or near them. The effect of such events can be minimized by surrounding them with ductile “buffer” clay that retards groundwater-driven adflow. An alternative concept is placement of HLW in very deep boreholes (VDH) where the rock is much less permeable and where the very salt, heavy groundwater is stagnant. The boreholes are proposed to be 4 km deep and grouped in a small number of sites. The upper 2 km parts, with temperatures lower than about 100oC, are sealed by being filled with perforated supercontainers with dense clay blocks, while the lower part contains supercontainers with waste canisters and dense clay blocks, raising the temperature between 2 and 4 km to 100-150oC. The holes are kept filled with clay mud into which the supercontainers are inserted where the rock contains few fractures, while concrete is cast where the rock is fracture-rich. In the upper part clay migrates through the perforated supercontainers and consolidates the mud. In the lower part clay the same process takes place where the clay block in each supercontainer is located, while the rest of the mud retains its original low density but undergoes stiffening. In the upper, sealed part of the hole, the consolidated clay will be much tighter than the surrounding rock, while in the lower part the mud will be more permeable but still capable of limiting water circulation within the hole. The paper compares the two repository principles and recommends closer examination of the very deep hole concept, which has obvious advantages respecting both performance and cost.

  • 330.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    El-Tekno AB.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    The role of crystalline rock for disposal of high-level radioactive waste (HLW)2015Inngår i: Vol. 15, s. 526-535Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The stress conditions in the host rock of HLW repositories, altered by construction and heat generated by the waste can cause large changes in groundwater flow, and failure of the repository. These shortcomings reduce the barrier role of the rock and the required effective isolation of HLW has to be provided by engineered barriers of which clay-embedded metal canisters are most important. The paper describes the performance of the nearfield rock of HLW packages according to two types of repositories: very long subhorizontal holes with large diameter (1.9 m) bored or blasted at 400-600 m depth, and bored 4 km deep holes with clay/concrete seals in the upper 2 km parts and HLW packages separated by clay/concrete seals in the lower 2 km parts. The most important difference between the two concepts is the much higher groundwater transmissivity of the rock in the shallow repository. A common feature is the need for rock support by filling the space between waste containers and rock with clay mud after installing the containers in shallow repositories, and by keeping the holes in deep repositories filled with clay mud from the start of boring the holes and throughout the installation of clay/concrete seals. Focus is on the role of rock discontinuities on the hydraulic and mechanical performances of the repository host rock at construction and under seismic and tectonic impact. Comparison of the two concepts shows that the one implying deep-disposal is superior but requires preparative steps in the waste placement phase.

  • 331.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Warr, Laurence
    Greifswald University, Geographical & Geological Department, Germany.
    Grathoff, Georg
    Greifswald University, Geographical & Geological Department, Germany.
    Pourbakhtiar, Alireza
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Hatem, Mohammed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    A talc-based cement-poor concrete for sealing boreholes in rock2013Inngår i: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 5, nr 3, s. 251-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deep investigation boreholes in crystalline rock for site selection of repositories for high-level radioactive waste are proposed to be sealed by installing a series of dense concrete and clay plugs. These should prevent radionuclides from leaking canisters at depth to migrate to the biosphere through the holes. The concrete seals will be installed where the holes intersect water-bearing fracture zones to serve as stable and low-permeable supports for adjacent clay plugs. Low porosity and microstructural stability must be guaranteed for many thousands of years and ordinary Portland cement with organic superplastizer will not fulfil the requirements since the high pH will cause degradation of contacting clay and the organic additive can produce colloids with a capacity to carry radionuclides up to the biosphere. Very cement-poor concrete (<8 %) based on low-pH cement and with talc as plasticizer is an option but it matures more slowly, which requires that the construction of seals is made so that sufficient bearing capacity for carrying overlying clay seals is reached.

  • 332.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Warr, Laurence
    Greifswald University, Geographical & Geological Department, Germany.
    Grathoff, Georg
    Greifswald University, Geographical & Geological Department, Germany.
    Purbakhtiar, Alireza
    Luleå University of Technology.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Ramqvist, Gunnar
    El-Tekno AB, Eltekno AB, Oscarshamn, Sweden.
    A study on cement-poor concrete with talc for borehole sealing in rock hosting radioactive waste2014Inngår i: Comunicações Geológicas, ISSN 0873-948X, E-ISSN 1647-581X, Vol. 101, nr 1, s. 71-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper describes the performance of a concrete intended for sealing deep boreholes in the host rock of radioactive repositories. The concrete will form plugs where fracture zones are intersected and be located between very tight seals of smectite clay installed where the surrounding rock is tight. The concrete must be able to carry the clay segments after a couple of days but the bearing capacity does not have to be very high since the clay soon adheres to the rock and carries itself. The concrete contains talc as superplasticizer since ordinary organic additives for reaching high fluidity at casting are unwanted. It has a low cement content for maintaining its low porosity after dissolution in a long time perspective.

  • 333.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Warr, Laurence N.
    Department of Geography and Geology, University of Greifswald, F.-L.-Jahn-Straße 17A, Germany..
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Condensed summary of current R&D on cementitious sealants for deep boreholes with HLW2017Inngår i: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 226, s. 192-198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cement-based materials for use as sealants in underground waste storages must be erosion-resistant and chemically stable. Placement of highly radioactive waste (HLW) in boreholes may require that the rock is cement-grouted and stabilized by constructing concrete plugs. Where smectitic clay seals are in contact with concrete there is mutual degradation, and low-pH cement with inorganic superplasticizers, like talc, are recommended for preparing the concrete. This paper reviews our current state-of-knowledge concerning the grout and concrete sealing very deep boreholes (DBD) for purpose of high-level radioactive waste disposal. In this concept, the lower 2 km section of 4 km deep holes bored in crystalline rock could host waste-containers while the upper parts are sealed by dense clay and concrete.1 The parts of such a hole that intersect fracture-poor rock are sealed with dense expandable clay while concrete is cast where fracture zones are intersected. The paper summarizes the available experimental results concerning the performance of grouts and concrete with talc as superplasticizer in contact with smectitic clay.

  • 334.
    Pusch, Roland
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Weston, Richard
    Division of Production and Mechanical Engineering, University of Lund.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Impact of scale on rock strength2016Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The scale dependence of the strength of virtually homogeneous rock is caused by the spectrum of discontinuities of different size and nature. This makes small samples significantly stronger and less deformable than larger ones. The strength reduction for larger volumes is defined and found to apply to rock volumes 500 times larger than standard samples tested in the laboratory. Recording of the creep strain in large-scale load tests show the strain rate to be strongly retarded and negligible for stresses lower than about 1/3 of the failure load. For higher stresses creep took place according to a log time law representing secondary creep that ultimately changed to tertiary creep and failure.

  • 335. Riechers, Jörg
    Impact of Drilling in Embankment Dams: A Comparative study between Water Powered DTH Hammer Drilling Technology and Hydraulic Top Hammer Drills2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Large geotechnical structures such as embankment dams and tailings dams are subject to high safety requirements. One of the key requirements is long-term stability in order to avoid incidents and failures as well as to ensure environmental safety during and after the operational phases. To ensure security, the instrumentation of existing embankment dams and tailings dams, using drilling technologies, is necessary for surveillance. Drilling in the structures of dams or in their foundations, however, always entails certain risks. Therefore, the selection of drilling technologies must be carried out carefully, taking into account the condition and sensitivity of each dam section. A continuous evaluation and development of existing drilling requirements is an important safety aspect.The main objective of this comparative study, implemented in collaboration between LKAB, Wassara AB, Sweco Infrastructure AB and Luleå University of Technology in Malmberget, Sweden, is to analyse the influence on surrounding soil of a water powered DTH hammer system and top hammer drillings with different setups during the drilling process. Covering an area of 800 m², an artificial dam with a height of 3 m was built and compacted in layers. The soil used was characterised as gravelly sand. Drillings were done vertical and inclined. Weight sounding tests before and after drilling, excavation of boreholes as well as soil sampling for further laboratory analysis have all been conducted. Complementing this research project, one vertical borehole with a depth of 30 m has been drilled with Wassara’s Lost Hammer concept (LHC) in the tailings dam of LKAB in Malmberget.This study concludes by stating that, for the analysed drilling formation, the average radius of influence on soil was identical (0.49 m along the borehole axis) for both the water powered DTH and the hydraulic top hammer system with a pre-drilling protective casing. Top hammer drillings in combination with a casing drilling system (Symmetrix) indicate an increased average zone of influence of 0.72 m around the boreholes. Measurements collected while drilling, correlated with laboratory analyses and weight sounding tests, reveal that the rearrangement of soil particles depends on the interaction of applied down-thrust, the vibration of the drill string, the amount of drained flushing water towards the adjacent soil and existing pressure conditions within the embankment structure.

  • 336.
    Rodriguez, Juan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Bhanbhro, Riaz
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Effect of vertical load on tailings particles2016Inngår i: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 6, nr 2, s. 115-129Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tailing dams could store hundreds, thousands or millions of cubic meters of tailings result of the mining extractive industry. Mechanical behavior of this man-made soil should be known in order to maintain a safe storage. Dykes rise up to form the dams and they are buildup with the same tailing material especially in the upstream method using the coarse part. The study uses oedometer classical test to determine the load effect over tailing coarse particles. Tailings are site specific and so its characteristics. It is necessary to understand the tailings degradations to achieve safe impounds. The study comprises four samples of one range-size tailing particles (e.g. 1-0.5, 0.5-0.25, 0.25-0.125, 0.125-0.063mm) subject to vertical load in traditional oedometers. Vertical load effects are measured using two dimensional image analysis and sieving. Results show that 0.063mm sample is the only one that has change in shape with low breakage (<1%) while the rest of the sizes have no shape change but high breakage is present especially in fraction 0.5mm. Settlements also are more pronounced in coarse fractions 0.5 and 0.25mm.

  • 337.
    Rodriguez, Juan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Bhanbhro, Riaz
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Shear Strength in Uniformed Sized Tailing ParticlesInngår i: International Journal of Geotechnical Engineering, ISSN 1938-6362, E-ISSN 1939-7879Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mining industry provides mineral to the modern society. Minerals are indispensable raw materials for commodities. A by-product of the mineral extraction is the mine waste also called tailings. Tailings are safety storage in tailing dams. Tailings dams troughs the history had had incidents and failures. Economic, environmental and social consequences of a tailing dam failure could be devastating. Soil strength is given by the consolidation, particle shape, stresses path, water content, hydraulic conductivity among other factors. Change on these factors produces changes in the soil strength. The development of economical and fast tests could improve the safety of the tailings deposits. Drained direct shear tests using uniformed graded tailing particles were performed. Three different size ranges 0.25, 0.125 and 0.063mm were used. Effect of particle size on shear strength and the effect of shearing on the tailing particles were studied. Normal consolidation pressure, void ratio, particle size and particle shape were monitored properties. Strength of the tailings was related with the monitored properties to suggest four empirical relations, two of them base in the morphology of the particle and two bases in the angularity. Results have shown that particle elongation diminishes the tailings strength but the angularity increases the strength. Particle size results are ambiguous and seem to be more related with the shape descriptor.

  • 338.
    Rodriguez, Juan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Mechanical weathering effect on tailing particles2016Inngår i: Proceedings of Nordic Conference on Soil Mechanics and Geotechnical NGM: Reykjavik, Iceland 25th – 28th of May 2016, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Over the last century the tailing volume generation has grown dramatically due to the mineral demand. Nowadays the mining industry is producing every year millions of tons of tailings. The storage of the tailings has become a challenge due to the increased storage capacity demanded. Physical risk associated to the tailings dams is the stability itself since tailing dams are considered a walk-away solution. Physical changes as breakage and shape occur to the tailing particles affecting the stability of the fills by reduced strength properties. In order to understand the reduction and shape changes of tailing particles degradation test by milling attrition (erosion) and image analysis was conducted. Uniform fractions 1-0.5, 0.5-025, 0.25-0.125 and 0.125-0.063mm were used.Results have shown that attrition agents e.g. ball attrition can increase the physical erosion but also change the shape of the particles compared with autogenous attrition. However particles shape has become more regular (less elongated) and rounded in coarse fractions 1-0.5 and 0.5-0.25mm while smaller fractions 0.25-0.125 and 0.125-0.063mm seems to have opposite behavior. Comparison with previous milling studies show consistent differences probably due to the breakage of the particles was the objective. In perspective if tailings become more rounded the strength could be compromised. More studies are needed to verify this.

  • 339.
    Rodriguez, Juan
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Edeskär, Tommy
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Particle shape quantities and measurement techniques: a review2013Inngår i: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 18/A, s. 169-198Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 340.
    Romelsjö, Anders
    et al.
    Karolinska Institutet.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Al-Ansari, Nadhir
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Pusch, Roland
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Brahme, Anders
    Karolinska Institutet.
    Dags kräva stopp för utarmat uran i vapen2012Inngår i: Goeteborgs - Posten, ISSN 1103-9345Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Vapenprojektiler och pansar dopat med uran kan orsaka cancer, missbildningar och död hos den som hanterar eller utsätts för dem. Svenska folket måste nu få veta om sådana vapen tillverkas av Bofors och om svenska soldater kommit i kontakt med dem. Det är också hög tid för riksdagen att verka för ett förbud mot dessa vapen, skriver bland andra professor Anders Romelsjö.

  • 341.
    Rostmark, Susanne
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Colombo, Manuel
    University of British Columbia, Vancouver.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Öberg, Gunilla
    University of British Columbia, Vancouver.
    Removal and Re-use of Tar-contaminated Sediment by Freeze-dredging at a Coking Plant Luleå, Sweden2016Inngår i: Water environment research, ISSN 1061-4303, E-ISSN 1554-7531, Vol. 88, nr 9, s. 847-851Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Submerged tar-contaminated sediments are generally very loose, which makes remediation challenging. We tested if a modified version of freeze-dredging could be used to remove and dewater such sediments in a canal down-stream a coking plant. PVC hoses carrying a heat medium were placed horizontally in the submerged sediments. Five days of freezing allowed straightforward removal of most of the sediments. Flat freeze cells were placed side by side in the canal to remove the rest. The freeze-thaw process increased the dry substance (DS) content from approximately 50 to 80%. Outdoors storage under rainy conditions did not re-wet the dried sediments. The material was successfully used as feed-stock in the coking plant, with the double cost-benefit of avoided transportation to deposit and reduced use of coal. The study demonstrates that freeze-dredging can facilitate removal, storage and beneficial re-use of submerged tar-contaminated sediments.

  • 342.
    Rostmark, Susanne
    et al.
    Luleå tekniska universitet.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Freeze dredging - an innovative technique for removal of contaminated sediments2004Inngår i: Mark och vatten i ett föränderligt samhälle: Geoteknisk forskardag 2004, Linköping: Statens geotekniska institut (SGI) , 2004, s. 109-109Konferansepaper (Annet vitenskapelig)
  • 343.
    Rostmark, Susanne
    et al.
    FriGeo AB.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Remediation of polluted sediments through deep freezing2003Inngår i: Proceedings from the Third International Disposal Conference: Karlskoga, Sweden, 10-11 November, 2003, Linköping: Linköping University Electronic Press, 2003Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Artificial ground freezing (AFG) is a well established technique first practised in South Wales in 1862. Since then many different temporary and permanent applications have been developed. AFG is mostly used in tunnels and for stabilising excavations, but there is an increasing interest in using AFG for environmental protection and for using freeze/thaw cycles for remediation of contaminated soil. Freeze dredging is a novel dredging technique developed at Luleå University of Technology in co-operation with industrial partners. The contaminated sediment is first stabilised by freezing, and then the frozen sediment is lifted up above the water with a minimum of disturbance of the surrounding soil. Full-scale field tests have been performed with very good results. It has been hypothesised that underwater freezing can be used also for removal or radioactive material, fragile containers with hazardous content, and ammunition. This paper describes the basic principles of the technology and lessons learned from the full scale tests. It also deals with considerations necessary for designing a system for underwater freezing of different materials.

  • 344.
    Rostmark, Susanne
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Removal of contaminated sediments by freeze-dredging2004Inngår i: Remediation of contaminated sediments - 2003: proceedings of the Second International Conference on Remediation of Contaminated sediments, Venice, Italy, September 30 - October 3, 2003 / ed.: Marco Pellei ..., Columbus, Ohio: Battelle Press , 2004, s. 227-234Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a small lake in the subarctic region of Sweden an area of 250 m 2 was dredged using a novel dredging technique: Freeze Dredging. Freeze Dredging is performed by freezing the sediment and lift it while frozen. During the operation approximately 28 tons of contaminated material was removed. The environmental monitoring showed no harmful redistribution of sediment. Levels of petroleum contamination in the dredged area was reduced by 90%. Overconsolidation caused by the freeze/thaw cycle reduced the water content when the material thawed. Freeze Dedging can be used for removal of contaminated sediments. The technique is especially aimed for sediments with low water content and sediments with debris, boulders and rocks.

  • 345. Rostmark, Susanne
    et al.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Maksimainen, E.
    Freeze dredging: underwater freezing or sediment remediation and rescue of objects at sea bottom2004Inngår i: Fjellsprengningsteknikk : Oslo, 25. november 2004 ; Bergmekanikk : Oslo, 26. november 2004 ; Geoteknikk : Oslo, 26. november 2004 / [ed] Bjørn Nilsen, Norsk Betongforening , 2004, s. 29.1-Konferansepaper (Annet vitenskapelig)
  • 346.
    Rönnqvist, Hans
    et al.
    RQV Teknik AB.
    Viklander, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Experimental Investigation of Suffusion in Dam Core Soils of Glacial Till2017Inngår i: ASTM geotechnical testing journal, ISSN 0149-6115, E-ISSN 1945-7545, Vol. 40, nr 3, s. 426-439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objectives of this study were to determine the susceptibility to suffusion of widely graded, non-plastic glacial till; to identify potential factors influencing susceptibility; and conversely, to determine grading characteristics that potentially eliminate suffusion susceptibility. A laboratory experimental program was performed on 12 non-plastic glacial till specimens. Four were natural glacial tills sourced from the cores of four existing embankment dams in Sweden, and the remaining eight were mixtures based on these tills with adjusted particle size distributions to obtain target gradations. Four specimens failed by suffusion. By comparing against stable specimens, these were characterized by fines content <20 %, sand fraction <25 %, and finer fraction <30 %. Conversely, gradations with higher fines content (> 25 %), which in this study corresponds to finer fraction >35 %, may provide additional limits to suffusion susceptibility of this kind of soil.

  • 347.
    Saarelainen, Seppo
    et al.
    VTT.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Instanes, Arne
    Opticonsult AB.
    Frost heave design of embankments for high-speed railways2001Inngår i: Proceedings of the Fifteenth International Conference on Soil Mechanics and Geotechnical Engineering: Istanbul, 27-31 August 2001, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 2001Konferansepaper (Fagfellevurdert)
  • 348.
    Sheng, D.
    et al.
    Luleå tekniska universitet.
    Axelsson, Kenneth
    Luleå tekniska universitet.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Frost heave due to ice lens formation in freezing soils. 1: Theory and verification1995Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 26, nr 2, s. 125-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A frost heave model which simulates formation of ice lenses is developed for saturated salt-free soils. Quasi-steady state heat and mass flow is considered. Special attention is paid to the transmitted zone, i.e. the frozen fringe. The permeability of the frozen fringe is assumed to vary exponentially as a function of temperature. The rates of water flow in the frozen fringe and in the unfrozen soil are assumed to be constant in space but vary with time. The pore water pressure in the frozen fringe is integrated from the Darcy law. The ice pressure in the frozen fringe is determined by the generalized Clapeyron equation. A new ice lens is assumed to form in the frozen fringe when and where the effective stress approaches zero. The neutral stress is determined as a simple function of the unfrozen water content and porosity. The model is implemented on an personal computer. The simulated heave amounts and heaving rates are compared with experimental data, which shows that the model generally gives reasonable estimation.

  • 349.
    Sheng, D.
    et al.
    Luleå tekniska universitet.
    Axelsson, Kenneth
    Luleå tekniska universitet.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Frost heave due to ice lens formation in freezing soils: 2, Field application1995Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 26, nr 2, s. 147-168Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An operational model for estimation of frost heave in field where stratified soil profile appears is presented. The model is developed from the research model described in part B. Soil layers are first classified into frost-susceptible layers (FSL) or non-frost-susceptible layers (NFSL). In an FSL, both heat flow and water flow are considered and ice lensing can occur. In a NFSL, only heat flow is possible and no ice lensing is allowed. The governing equations for heat and mass transfer are established for the time period when the frost front is moving within FSL. Capillarity and unsaturation are also considered. The operational model is verified by field measurements of heave amounts. Examples of application are given.

  • 350.
    Sheng, D,
    et al.
    Luleå tekniska universitet.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Sensitivity analysis of frost heave: a theoretical study1993Inngår i: Frost in geotechnical engineering: proceedings of the 2nd international symposium on Frost geotechnical engineering, Rotterdam: Balkema Publishers, A.A. / Taylor & Francis The Netherlands , 1993Konferansepaper (Fagfellevurdert)
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