J. R. Booker

Barrier Systems for Waste Disposal Facilities

1. Basic Concepts. 2. Leachate Characteristics and Collection. 3. Clay Liners: Compaction, Hydraulic Conductivity and Clay Mineralogy. 4. Clay/Leachate Compatibility by Measurement of Hydraulic Conductivity. 5. Flow Modelling. 6. Chemical Transfer by Diffusion. 7. Contaminant Transport Modelling. 8. Evaluation of Diffusion and Distribution Coefficients. 9. Field Studies of Diffusion and Hydraulic Conductivity. 10. Contaminant Migration in Intact Porous Media: Analysis and Design Considerations. 11. Migration in Fractured Media: Analysis and Design Considerations. 12. Geosynthetic Clay Liners (GCLs). 13. Geomembrane Liners. 14. Covers. 15. Geotechnical and Related Design Issues. 16. Integration of Hydrogeology and Engineering in Barrier Design and Impact Assessment. Index.

Clayey Barrier Systems for Waste Disposal Facilities

Basic concepts. Introduction. Overview of barrier systems. Transport mechanisms and governing equations. Complicating factors. Modeling the finite mass of contaminant. Modeling a thin permeable layer as a boundary condition. Hand solutions so some simple problems. Summary. Design considerations. Introduction. Impact assessment. Waste and leachate composition. Leachate mounding and collection. Leakage through liners. Leak detection systems. Landfill capping and the control of infiltration. Choic of barrier system and service life considerations. Geotechnical considerations. Summary. Clayey barriers: compaction, hydraulic conductivity and clay mineralogy. Introduction. Methods of assessing hydraulic conductivity. Compaction-permeability relationships. Clay mineralogy. Clay colloid chemistry. Clay-leachate compatibility by measurement of hydraulic conductivity. Introduction. Soil- MSW leachate compatibility. Compatibility of clays with liquid hydrocarbon permeants. Summary and conclusions. Flow modeling. Introduction. One-dimensional flow models. Analysis of two-and three-dimensional flow. Finite difference approximation. Application of the finite element method to the analysis of plane flow. Boundary element methods. Chemical transfer by diffusion. Introduction. Free solution diffusion (Do). Diffusion through soil. Steady-state diffusion. Transient diffusion. Use of laboratory and field profiles to measure diffusion coefficient De. Diffusion during hydraulic conductivity testing for clay - leachate compatibility. Summary and conclusions. Contaminant transport modeling.Introduction. Analytical solutions. Application of Laplace transforms to develop a finite layer solution for a single layer. Contaminant transport into a single layer considering a landfill of finite mass and an underlying aquifer. Finite layer analysis. Contaminant migration in a regularly fractured medium. Determination of diffusion and distribution coefficients. Introduction. Obtaining diffusion and partitioning/distribution coefficients: basic concepts. Example tests for obtaining diffusion and distribution coefficients for inorganic contaminants. Dispersion at low velocities in clayey soils. Effective porosity. Distribution coefficients and nonlinearity. Effect of leachate composition, interaction and temperature. Diffusion and sorption of organic contaminants. Use of field profiles to estimate diffusion coefficients. Summary and conclusions. Field studies of diffusion and hydraulic conductivity. Introduction. Examples of long-term field diffusion. Examples of short-term diffusion. Hydraulic conductivity of contaminated clay liners. Contaminant migration in intact porous media: analysis and design considerations. Introduction. Mass of contaminant, the ref erence height of leachate, Hr, and the equivalent height of leachate, Hf. Development of a contaminant plume. Effect of base velocity. Effect of horizonta

An investigation of the stability of numerical solutions of Biot's equations of consolidation

Abstract In this paper a finite element formulation based on approximation in the Laplace transform space, is given for Biots Consolidation theory. Various integration schemes are proposed and conditions under which these integration schemes are stable are investigated. The results are illustrated by means of a numerical example.

ELASTO-PLASTIC CONSOLIDATION OF SOIL

Abstract A theory of the behaviour of an ideal mass of two-phase soil is developed. This theory unites the usually separately considered aspects of analytical soil mechanics of settlement and deformation; time dependent consolidation; and yielding leading to collapse of the mass. The theory assumes the soil to be an elasto-plastic permeable material and a finite element approximation of the resulting equations is derived through the principle of virtual work. Two example problems are treated numerically.

A THEORY OF FINITE ELASTIC CONSOLIDATION

Presented in this paper is a general theory describing the consolidation of a porous elastic soil. The formulation allows for the occurrence of finite geometry changes and finite elastic strains during the consolidation process. The governing equations have been cast in a rate form and the laws which determine deformation and pore fluid flow, i.e. Hookes law and Darcys law, are presented in a frame indifferent manner. A numerical technique is described that provides an approximate solution to the governing equations. The theory and the solution technique are illustrated by several examples of practical interest.

Finite element analysis of excavation

Abstract The finite element method has often been used to simulate excavation. When the soil is linearly elastic, the results of excavation should be independent of the number of stages in the excavation process, and lack of such independence indicates an incorrect procedure. The simple direct method described in this paper provides the required independence in the case of linearly elastic materials, and hence can be used for multi-stage excavation in non-linear problems without excessive errors. However methods whose errors increase with the number of stages of excavation are quite unsuitable for non-linear problems. Alternative methods of analysis, errors arising from the inability of the elements to model adequately the stress gradients near the toe of the excavation and excavation adjacent to a diaphragm wall are discussed.

Elastic consolidation around a deep circular tunnel

A method of analysis is presented for the consilidation of a linear elastic soil due to the cutting of a long and deep circular tunnel. Solutions have been obtained for the time dependent displacements and stress changes occurring in the soil surrounding the tunnel opening.

THE CONSOLIDATION OF A FINITE LAYER SUBJECT TO SURFACE LOADING

Abstract In this paper a solution to the problem of the consolidation of a clay layer resting on a rough rigid base and subject to general surface loading is given. The solution is evaluated for the particular cases of a uniformly loaded strip, circle and square for a variety of Poissons ratios. The results are compared with previous solutions which have used the less realistic assumption that the clay layer rests on a smooth rigid base.

Finite element analysis of coupled thermoelasticity

Most thermal stress analyses assume that the determination of the temperature field is uncoupled from that of the stress and displacement fields, while assuming that the stress and displacement fields depend on the temperature field. This semi-coupled approach to thermoelasticity is not entirely consistent. In this paper a variational principle for the fully coupled theory of thermoelasticity is developed. This is used to obtain a finite element approximation which is then compared with analytical solutions. An assessment is also made of the importance of the full coupling.

Withdrawal of a compressible pore fluid from a point sink in an isotropic elastic half space with anisotropic permeability

Abstract The complete solution is presented for the transient effects of pumping fluid at a constant rate from a point sink embedded in a saturated, porous elastic half space. It is assumed that the medium is homogeneous and isotropic with respect to its elastic properties and homogeneous but anisotropic with respect to the flow of pore fluid. The soil skeleton is modelled as an isotropic linear elastic material obeying Hookes law while the pore fluid may be compressible with its flow governed by Darcys law. The solution has been evaluated for a particular value of Poissons ratio of the solid skeleton, i.e. 0.25, and the results have been presented graphically in the form of isochrones of excess pore pressure and surface profile for the half space. The solutions presented may have application in practical problems such as dewatering operations in compressible soil and rock masses and in the extraction of petroleum products from the crust of the earth.