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Some laboratory measurements of permeability of Bothkennar clay in relation to soil fabric
89A 932138 Some laboratory measurements of permeability of Bothkelmar day in relation to soil fabric Little, J A; Wood, D M; Paul, M A; Bouazza, A Geoteclmique V42, N2, June 1992, P355-361 Vertical and horizontal permeabilities have been measured on samples of Bothkennar clay in controlled flow tests using hydraulic oedometers and have been estimated from interpretation of consolidation tests. The permeability anisotropy seen is consistent with the assignment of different fabrics found in parallel engineering geological studies.
932139 Leachate flow rate behavior through geotextile and soil filters and possible remediation methods Koerner, G R; Koerner, R M Geotext Geomem V11, N4/6, 1992, P401-430 Drainage systems at the bases of landfills, waste dumps, and heap leach pads include a geotextile and/or soil filter to retain solid particles. Laboratory tests with 6 different types of leachate and 16 filter combinations showed permeability decreasing with time, reaching a steady state after about 6 months, as a result of sediment and/or biological clogging. Four remedial techniques were investigated. They were, in decreasing order of effectiveness, water backflush, leachate backflush, nitrogen gas backflush, and vacuum declogging. The benefits of biocide treated geotextiles were not convincingly demonstrated. Long term minimum permeability values require quantification.
932140 Parameter estimation of the coefficients in soil hydraulic equations from steady-state unsaturated flow Richie, E B; Schnabel, R R Ground Water V30, N4, July-Aug ]992, P515-522 A parameter estimation procedure using nonlinear least squares regression of steady state matric potential along an unsaturated soil column to an analytical equation describing the matric potential distribution is presented. Total mass of water in the column at steady state, saturated water content, and steady state flow rate are also required for parameter estimation. The procedure has been verified using synthetic data and implemented in the laboratory. Coefficients in Campbell and van Genuchten soil hydraulic equations have been evaluated. Two alternative approaches to determine some of the parameters are also presented.
932141 Nonlinear water diffusion in unsaturated porous solid materials Lin, S H Int J Engng Sci V39, N12, Dec 1992, P1677-1682 Water diffusion in porous materials, of interest in many disciplines, is investigated. A highly nonlinear water contentdependent function is used to represent the hydraulic diffusivity of water diffusion. The resulting physical model is tackled using the orthogonal collocation method. Numerical simulations of water diffusion in various unsaturated rocks and construction materials agree well with experimental observations.
932142 Boundary integral method for steady flow in unsaturated porous media Martinez, M J; McTigue, D F lnt J Num Anal Meth Geomech V16, N8, Aug 1992, P581601 If a hydraulic conductivity function which varies exponentially with capillary-head pressure is assumed, the governing equation for steady flow in a homogeneous unsaturated porous medium can be written in a linear (Fokker-Planck) form. This equation is amenable to numerical solution by the boundary integral equation method. The hydraulic conductivity function assumed is known to be a reasonable approximation over limited ranges of pressure head. BIEM solutions and those from a finite element code that fully solves the nonlinear problem are compared for cases of flow in tuff and moisture distribution around a tunnel. Good agreement is seen with considerable savings in computer time if the BIEM is used. 932143 Zone of disturbance around blasted tunnels at depth Pusch, R; Stanfors, R lnt J Rock Mech Min Sci V29, N5, Sept 1992, P447-456 Two large scale field tests in granite at the Aspo site, Sweden, included determination of effects of blasting and stress changes on the near-field rock, and have led to a preliminary model of excavation damage. The blast-disturbed zone around the tunnel periphery varied in depth from a few decimeters to over lm, depending on charge. Axial hydraulic conductivity enhancement of 2-3 orders of magnitude is seen in this zone. Stress changes cause similar enhancement of up to 1 order of magnitude in a zone up to 50% tunnel radius, if the tunnel is suitably oriented with respect to fracture sets. This change is associated with reduction in radial conductivity of about 5 times. 932144 Water throughflow and the physical effects of deformation on sedimentary glacier beds Murray, T; Dowdeswell, J A J Geopkys Res V97, NB6, June 1992, P8993-9002 Waterflow in the sedimentary, unlithified, and potentially deformable bed beneath a glacier may be by sheet flow at the interfaces, Darcian throughflow, or through preferential channels. Laboratory deformation tests have been carried out to simulate the effects of active deformation on subglacial sediments. Particle alignment parallel or subparallel to the principal strain and dilation where active deformation has occurred are found. Increased permeability results in increased flow rate through the bed parallel to the deformation. Water retained in the high permeability layer may adversely affects its stability. 932145 Hydraulic conductivity of noncohesive soils Aberg, B J Geotech Engng Div ASCE Vl18, N9, Sept 1992, P13351347 A simple stochastic model of void structures of granular materials and equations to calculate the void ratio from the grain size distribution are presented in a companion paper. Using this as a basis, equations are developed for the hydraulic conductivity of cohesionless soils or similar materials compacted to a dense state. Results from large-scale permeameter tests on gravel and crushed rock support these equations and are used in evaluation of the numerical coefficients.
© 1993 Pergamon Press Ltd. Reproduction not permitted
932139 Leachate flow rate behavior through geotextile and soil filters and possible remediation methods Koerner, G R; Koerner, R M Geotext Geomem V11, N4/6, 1992, P401-430 Drainage systems at the bases of landfills, waste dumps, and heap leach pads include a geotextile and/or soil filter to retain solid particles. Laboratory tests with 6 different types of leachate and 16 filter combinations showed permeability decreasing with time, reaching a steady state after about 6 months, as a result of sediment and/or biological clogging. Four remedial techniques were investigated. They were, in decreasing order of effectiveness, water backflush, leachate backflush, nitrogen gas backflush, and vacuum declogging. The benefits of biocide treated geotextiles were not convincingly demonstrated. Long term minimum permeability values require quantification.
932140 Parameter estimation of the coefficients in soil hydraulic equations from steady-state unsaturated flow Richie, E B; Schnabel, R R Ground Water V30, N4, July-Aug ]992, P515-522 A parameter estimation procedure using nonlinear least squares regression of steady state matric potential along an unsaturated soil column to an analytical equation describing the matric potential distribution is presented. Total mass of water in the column at steady state, saturated water content, and steady state flow rate are also required for parameter estimation. The procedure has been verified using synthetic data and implemented in the laboratory. Coefficients in Campbell and van Genuchten soil hydraulic equations have been evaluated. Two alternative approaches to determine some of the parameters are also presented.
932141 Nonlinear water diffusion in unsaturated porous solid materials Lin, S H Int J Engng Sci V39, N12, Dec 1992, P1677-1682 Water diffusion in porous materials, of interest in many disciplines, is investigated. A highly nonlinear water contentdependent function is used to represent the hydraulic diffusivity of water diffusion. The resulting physical model is tackled using the orthogonal collocation method. Numerical simulations of water diffusion in various unsaturated rocks and construction materials agree well with experimental observations.
932142 Boundary integral method for steady flow in unsaturated porous media Martinez, M J; McTigue, D F lnt J Num Anal Meth Geomech V16, N8, Aug 1992, P581601 If a hydraulic conductivity function which varies exponentially with capillary-head pressure is assumed, the governing equation for steady flow in a homogeneous unsaturated porous medium can be written in a linear (Fokker-Planck) form. This equation is amenable to numerical solution by the boundary integral equation method. The hydraulic conductivity function assumed is known to be a reasonable approximation over limited ranges of pressure head. BIEM solutions and those from a finite element code that fully solves the nonlinear problem are compared for cases of flow in tuff and moisture distribution around a tunnel. Good agreement is seen with considerable savings in computer time if the BIEM is used. 932143 Zone of disturbance around blasted tunnels at depth Pusch, R; Stanfors, R lnt J Rock Mech Min Sci V29, N5, Sept 1992, P447-456 Two large scale field tests in granite at the Aspo site, Sweden, included determination of effects of blasting and stress changes on the near-field rock, and have led to a preliminary model of excavation damage. The blast-disturbed zone around the tunnel periphery varied in depth from a few decimeters to over lm, depending on charge. Axial hydraulic conductivity enhancement of 2-3 orders of magnitude is seen in this zone. Stress changes cause similar enhancement of up to 1 order of magnitude in a zone up to 50% tunnel radius, if the tunnel is suitably oriented with respect to fracture sets. This change is associated with reduction in radial conductivity of about 5 times. 932144 Water throughflow and the physical effects of deformation on sedimentary glacier beds Murray, T; Dowdeswell, J A J Geopkys Res V97, NB6, June 1992, P8993-9002 Waterflow in the sedimentary, unlithified, and potentially deformable bed beneath a glacier may be by sheet flow at the interfaces, Darcian throughflow, or through preferential channels. Laboratory deformation tests have been carried out to simulate the effects of active deformation on subglacial sediments. Particle alignment parallel or subparallel to the principal strain and dilation where active deformation has occurred are found. Increased permeability results in increased flow rate through the bed parallel to the deformation. Water retained in the high permeability layer may adversely affects its stability. 932145 Hydraulic conductivity of noncohesive soils Aberg, B J Geotech Engng Div ASCE Vl18, N9, Sept 1992, P13351347 A simple stochastic model of void structures of granular materials and equations to calculate the void ratio from the grain size distribution are presented in a companion paper. Using this as a basis, equations are developed for the hydraulic conductivity of cohesionless soils or similar materials compacted to a dense state. Results from large-scale permeameter tests on gravel and crushed rock support these equations and are used in evaluation of the numerical coefficients.
© 1993 Pergamon Press Ltd. Reproduction not permitted