Continuum models for contaminant transport in fractured porous formations

Continuum models for contaminant transport in fractured porous formations

14A 891106 Direct determination of permeability of clay under embankment 891110 Continuum models for contaminant transport in fractured porous format...

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14A 891106 Direct determination of permeability of clay under embankment

891110 Continuum models for contaminant transport in fractured porous formations

Leroueil, S; Diene, M; Tavenas, F; Kabbaj, M; La Rochelle, P

Berkowitz, B; Bear, J; Braester, C

J Geotech Engng Div ASCE

V114, N6, June 1988. P645-657

A method to determine the ‘real’ in situ coefficient of permea-

bility at various depths in a foundation and at various times and strains has been developed. The method requires Darcy’s law to be valid, consolidation to be I-dimensional and the soil to be fully saturated. Knowledge of the evolution with time of pore pressures and deep settlements is necessary. The method is applied to a test embankment satisfying these conditions and results compared with those determined with laboratory and in situ techniques. The proposed method gives slightly higher results than laboratory tests. Coefficient of permeability determined from self-boring permeameters is recommended.

Water Resour Res V24, N8. Aug 1988, PI225I236

Contaminant transport in a homogeneous, isotropic fractured porous formation is considered. Mathematical and numerical models to simulate flow and contaminant transport in a 2-D fractured porous domain were developed, which allow transport by advection, diffusion and dispersion in both fractured and porous block domains. Results were compared with an existing analytical solution and showed, for the range of considered parameter values, a single continuum model is sufficient for modelling contaminant transport. 891111 Predicting the hydraulic conductivity of compacted clays

Harrop-Williams, 891107 Geostatfstical analysis of field hydraulic conductivity in compacted clay

Rogowski, A S; Simmons, D E Math Geol V20, N4. May 1988. P423-446

Experiments were undertaken to evaluate true values of hydraulic conductivity (k) and how they should be estimated, since laboratory values of k rarely agree with field estimates. A constant water level was maintained over a 0.3m compacted clay layer, and inflow and outflow rates monitored. The distribution of outflow rates suggested the presence of macropores and preferential flow through the macropores, so probability kriging was applied to reevaluate distribution of flux rates and possible location of macropores. Variogram analysis of outflows suggested sampling at 50 randomly chosen locations was adequate. This was confirmed by comparing simulated scenarios based on all available data with conditional simulations based on randomly chosen locations. 891108 Dispersion in heterogeneous porous media 1. Local volume averaging and large-scale averaging

Plumb, 0 A; Whitaker, S Water Resour Res V24. N7. July 1988. P913-926

A theory for dispersion in heterogeneous porous media has been developed using volume averaging at 2 scales. The model allows for prediction of the effect of heterogeneities on dispersion coefficient and a transport equation having 2 additional time dependent terms not in the conventional convection-dispersion equation.

K

Proc International Symposium on Prediction and Perfomance in Geotechnical Engineering, CaIgary, 17-19 June I987 P207209. Pub1 Rotterdam: A A Balkema. 1987

A theoretical relation is developed between the hydraulic conductivity and the easily measured dry unit weight and moisture content of a compacted clay liner. The development assumes that, due to low permeability of compacted clays, the soil never attains complete saturation and the line of optimum is below the zero air voids curve. The analysis then follows from the point of view of flow through unsaturated porous media. Auth. 891112 Overview of groundwater modelling

Pinder, G F Proc NA TO Advanced Research Workshop on Advances in Analytical and Numerical Groundwater Flow and Qua&y ModeRing, Lisbon, 2-6 June 1987 PlI9-134. Pub1 Dordrecht: Reidel. 1987

The development of numerical modelling of groundwater flow is reviewed. Saturated and unsaturated flow, contaminant transport, and multiphase flow, especially hydrocarbon, water, and air, are discussed. Areas under investigation are described. The many mathematical techniques used are illustrated, including classical, integrated, Galerkin, and collocation finite element analysis, hybrid finite element/finite difference methods, boundary element analysis, method of characteristics, and iterative methods. 83 refs. 891113 Comparison of fast equation solvers for groundwater flow problems

891189 Dispersion in heterogeneous porous media 2. Predictions for stratified and two-dimensional spatial periodic systems

Plumb, 0 A; Whitaker. S Water Resour Res V24. N7. July 1988. P927-938

Theory of dispersion in porous media is applied to a stratified porous medium and a simple 2-D spatially periodic heterogeneous porous medium. Comparison of predicted large-scale dispersion coefhcients with experimental results shows good agreement. Theoretical calculations show that heterogeneities can result in dispersion coefficients much larger than those determined in the laboratory using randomly packed beds of uniform spheres, and that local heterogeneities in randomly packed beds of uniform spheres play an important role in dispersion coefficients. 8

Schmid, G; Braess, D Proc NATO Advanced Research Workshop on Advances in Anut’yticuf and Numerical Groundwtater FIow aud Qua&y Moaklling, Lisbon, 2-6 June 1387 PI73-188. Pub1 Dordrecht: Reidel. 1987

Simulation models in groundwater management are becoming ever larger, and to save computer time, equation solvers of high efficiency are chosen, especially for time dependent or nonlinear models. Direct Cholesky or frontal solvers, conjugate gradient techniques, and multi-grid methods are used. The PCG method is compared with direct equation solvers for an areal model. A two dimensional dam problem is investigated using both uniform mesh and multigrid approaches. The superiority of PCG and multigrid methods is illustrated.

1989 Pergamon Press plc. Reproduction

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