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SUMMARYA new framework for thedevelopment of constitutive models based on certain aspectsof physical theoriesof plasticity is proposed. The resulting Multi-laminate model of clays has the same response as the Critical state model provided no rotation of principal stress axes takes place during plastic flow.The influence of rotation of the principal stress axes on the volumetric and deviatoric plastic strains has been numerically evaluated. In undrained saturated, normally consolidated clays considerable excess pore pressure may build up due to rotation of the principal axes only. Numerical studies of the collapse of footings indicate that significant rotations do not take place in this class of problems and consequently the collapse load is only marginally reduced.

SUMMARYA new model for rocks and rock-like material with multiple planes of weakness is proposed. The behaviour of the assembly applies tensile and Mohr-Coulomb shear limits on each such plane with possible strain dependence of frictional properties. The visco-plastic algorithm which allows the incorporation of time effects is used to obtain static solutions.The model is illustrated in actual context by applications to stability of rock slopes and behaviour of tunnels.A generalization of the model to include arbitrary three-dimensional distribution of laminae in 'quasi-plane strain' is included. The effect of various flow rules adopted for plastic straining is indicated.

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This paper presents a three-dimensional coupled bonded particle and lattice Boltzmann method (BPLBM) with an immersed moving boundary scheme for the fluid-solid interaction. It is then applied to investigate the erosion process of soil particles in granular filters placed within earth dams. The microscopic migration of soil particles can be clearly visualised as the movement of particles can be directly recorded. Three granular filters with different representative size ratios are simulated and the numerical results are seen to match the empirical criteria. In addition, the effect of the representative size ratio of granular filters, hydraulic loading and erosion time are discussed.

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