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Variable-aperture fracture network model for flow and transport in fractured rocks at different scales
289A 935161 Modelling of coupled hydraulic thermal and mechanical processes in the simulation of hot dry rock reservoir behaviour Kohl, T; Evans, K F; Hopkirk, R J; gybach, L Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 P551-558. Publ California; Lawrence Berkeley Laboratory, 1992 The finite element code FRACTure has been developed to model the coupled processes in a hot dry rock geothermal system. Thermal and hydraulic coupling, the nonlinear joint model, and elastic coupling are described. The basic considerations of simulation, fracture and medium geometry, and the physical processes of simulation steps, hydraulic processes, thermal processes, and elastic processes, are outlined. Results are presented of two simulations of long term system behaviour. 935162 Effects of excavation on water inflow to a drift Long, J C S; Olsson, O; Martel, S; Black, J Proe Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 P559-570. Publ California; Lawrence Berkeley Laboratory, 1992 At the Stripa Mine Project in Sweden, inflow into a series of parallel boreholes on the periphery and in the centre of a future drift was measured before and after excavation of the drift. Inflow after excavation was nearly an order of magnitude lower than before. Effects of stress changes, ventilation, excavation blasting, chemical precipitation, and degassing of the water on the flow have been examined. Degassing as the pressure of water is dropped to atmospheric is thought to be the major contributor to the skin effect of permeability surrounding the tunnel. 935163 Variable-aperture fracture network model for flow and transport in fractured rocks at different scales Nordqvist, A W; Tang, Y W; Tang, C F; Dverstorp, B; Andersson, J Proc Conference on Fractured and Jointed Rock Masses, Lake Tahoe, 3-5 June 1992 P579-586. Publ California; Lawrence Berkeley Laboratory, 1992 VAPFRAC (Nordqvist et al, 1992) is outlined. A network of fractures is first generated. Each fracture surface is discretized and geostatistical methods used to generate the spatially varying aperture for each element. Flow pattern and fracture transmissivity through each fracture are calculated. A frequency distribution of residence times for transport of particles through each fracture is also computed. Transmissivities and frequency times collected are assigned to the fractures in a random selection. These are then used in solution of flow through the fracture network and in particle-tracking calculations of solute transport. 935164 Correlation of sedimentulogic properties and saturated hydraulic conductivities of sedimentary interbeds at the Idaho National Engineering Laboratory Test Site E Pudney, W; Ore, H T; Welhan, J Proc 28th Symposium on Engineering Geology and Geoteclmical Engineering, Boise, 1-3 April 1992 P406-418. Publ Pocatello: Idaho State University, 1992 Hydraulic properties and sedimentologicai characteristics at the INEL site in the central part of the Eastern Snake River Plain were evaluated to assess potential for pollution of the underlying aquifers. The sediments are of fluvial, lacustrine, and aeolian origins. Interbeds at Test Site E varied in thickness from less than lm to over 15m. One calcified horizon has
been identified. Saturated hydraulic conductivity has been correlated with grain size, bulk density, porosity, and degree of cementation to depth of 330m. 935165 Prediction of I-D pollutant migration in stabilization of clayliners Chin, R Y P Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 VI, P385-388. Publ Thailand: Southeast Asian Geotechnical Society, 1991 The use of stabilised weathered mudstone as a landfill liner material in Taiwan has been investigated. Admixtures of the compacted clay with 6-20% of MSK hardening additive, a local product of industrial and mineral wastes, has been evaluated. Strength and permeability values achieved over a 28 day curing period are illustrated. 1-D pollutant migration in a hypothetical landfill has been modelled using the analysis of Rowe and Booker (1985).
Compressibility, swelling and consolidation See also: 935260, 935351, 935363 935166 Framework for the behaviour of unsaturated expansive clays Gens, A; Alonso, E E Can Geotech J 1129, N6, Dec 1992, P1013-1032 An existing general formulation (Alonso et al, 1987) to describe nonexpansive unsaturated soils has been extended for the case of expansive clays. It is based on a distinction within the material of a microstructural level at which basic swelling of active minerals occurs and a macrostructural level responsible for major structural rearrangements. By coupling actions at these two levels, it is possible to reproduce major features of the behaviour of unsaturated expansive soils. Comparisons of model predictions and data from the literature are examined. 935167 Effective stress concept in saturated sand-clay buffer Graham, J; Oswell, J M; Gray, M N Can Geoteeh J V29, N6, Dec 1992, P1033-1043 A series of tests was carried out on compacted sand/bentonite specimens to examine the application of the effective stress concept to dense compacted, plastic clays. The tests indirectly investigate the proposition that behaviour of the mixture can be expressed in terms of effective stresses defined as the tensor differences between externally applied total stresses and pore pressures measured outside the cell. Within experimental errors, results support the use of effective stress concepts to describe both consolidation and shear. Because of electrochemical contributions to the interparticle forces for clays, the conditions under which the concept is applicable are restricted. 935168 Water uptake and swelling properties of unsaturated bentonite buffer materials. Note Kanno, T; Wakamatsu, H Can Geoteeh J V29, N6, Dec 1992, P1102-1107 Water diffusivity and development of swelling pressure were studied for blocks of highly compacted Japanese Na bentonite and bentonite-sand mixtures during unsaturated water uptake. Water diffusivity was approximately the same as that for Wyoming bentonite MX-80. A model is developed for swelling pressure which closely describes test results except in early stages of uptake.
© 1993 Pergamon Press Ltd. Reproduction not permitted
been identified. Saturated hydraulic conductivity has been correlated with grain size, bulk density, porosity, and degree of cementation to depth of 330m. 935165 Prediction of I-D pollutant migration in stabilization of clayliners Chin, R Y P Proc Ninth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Bangkok, 9-13 December 1991 VI, P385-388. Publ Thailand: Southeast Asian Geotechnical Society, 1991 The use of stabilised weathered mudstone as a landfill liner material in Taiwan has been investigated. Admixtures of the compacted clay with 6-20% of MSK hardening additive, a local product of industrial and mineral wastes, has been evaluated. Strength and permeability values achieved over a 28 day curing period are illustrated. 1-D pollutant migration in a hypothetical landfill has been modelled using the analysis of Rowe and Booker (1985).
Compressibility, swelling and consolidation See also: 935260, 935351, 935363 935166 Framework for the behaviour of unsaturated expansive clays Gens, A; Alonso, E E Can Geotech J 1129, N6, Dec 1992, P1013-1032 An existing general formulation (Alonso et al, 1987) to describe nonexpansive unsaturated soils has been extended for the case of expansive clays. It is based on a distinction within the material of a microstructural level at which basic swelling of active minerals occurs and a macrostructural level responsible for major structural rearrangements. By coupling actions at these two levels, it is possible to reproduce major features of the behaviour of unsaturated expansive soils. Comparisons of model predictions and data from the literature are examined. 935167 Effective stress concept in saturated sand-clay buffer Graham, J; Oswell, J M; Gray, M N Can Geoteeh J V29, N6, Dec 1992, P1033-1043 A series of tests was carried out on compacted sand/bentonite specimens to examine the application of the effective stress concept to dense compacted, plastic clays. The tests indirectly investigate the proposition that behaviour of the mixture can be expressed in terms of effective stresses defined as the tensor differences between externally applied total stresses and pore pressures measured outside the cell. Within experimental errors, results support the use of effective stress concepts to describe both consolidation and shear. Because of electrochemical contributions to the interparticle forces for clays, the conditions under which the concept is applicable are restricted. 935168 Water uptake and swelling properties of unsaturated bentonite buffer materials. Note Kanno, T; Wakamatsu, H Can Geoteeh J V29, N6, Dec 1992, P1102-1107 Water diffusivity and development of swelling pressure were studied for blocks of highly compacted Japanese Na bentonite and bentonite-sand mixtures during unsaturated water uptake. Water diffusivity was approximately the same as that for Wyoming bentonite MX-80. A model is developed for swelling pressure which closely describes test results except in early stages of uptake.
© 1993 Pergamon Press Ltd. Reproduction not permitted