Soil modelling and numerical methods

Introduction

Design objectives; Theoretical considerations; Physical and analytical models.

Elastic models

Characteristics of soil behaviour; Strain increments and stress variables; Elasticity; Drained and undrained triaxial tests; Measurement of elastic parameters: oedometer, in-situ geophysics, plate loading, pressuremeter, anisotropy; Nonlinearity: secant and tangent stiffness; Advantages and limitations of elastic models.

Elastic-plastic models

Yield surface; Tresca criterion; Von-Mises criterion; Mohr- Coulomb criterion; Hardening models; Plastic flow rules.

Elastic

Perfectly plastic Mohr-Coulomb model; Elastic properties; Yield criterion; Flow rule; Elastic-plastic stiffness matrix; Selection of soil parameters.
Extended Mohr-Coulomb model

Clay-clay model

3D space; Isotropic consolidation; Critical state line; Model ingredients; Drained and undrained tests on NC clay; Elastic properties; Yield surface; Flow rule; Hardening rule; Compliance matrix.

Stress paths

Foundation loading, Slope stability; Stress path, 2D and 3D stress spaces; Examples of stress paths; Pore pressure changes; Application of stress paths.

Finite element method

Introduction; How the method works; Mathematical foundations; Nodes, elements and shape functions; Principle of virtual displacement; External work; Internal work.