TABLE OF CONTENTS The essential features of soil behaviour include: soil acts as a multi-phase material, soil response is non-linear and path-dependent, soil deformation include irrecoverable (plastic) strains, soils may dilate or compact, soil response is influenced by its load history, natural soils are anisotropic, and soils exhibit time-dependent behaviour. Ideally a perfect soil model would be able to predict these soil behaviour under all type of loading condition.
An increasing number of stress-strain relations have been formulated to model the behaviour of soils. These models can be grouped into linear elastic, non-linear elastic (hyperelasticity, hypoelasticity), variable moduli, elasto-plastic, elastovisco-plastic, cap models and hypoplasticity. Several references can be cited in connection with the formulation of constitutive soil models: Duncan and Chang 1970; Naylor and Pande 1981; Evgin and Eisenstein 1985; Britto and Grun 1987; Mizuno and Chen 1986; Chen and McCarron 1986; McCarron and Chen 1987; Hayashi and Yamanouchi 1986; Gudehus 2002; Chen and Mizuno 1990; Kirkgard and Lade 1993; Brinkgreve 2002; etc. The development of the models have been briefly reviewed in the following sub-sections.
All the numerical analysis of practical projects and parameter studies in this book are conducted using the finite element program "PLAXIS". Therefore, the constitutive soil models included in this program, their advantages and limitations in connection with excavation in soft normally consolidated soil, the soil parameters required and their evaluation is briefly assessed in this chapter.
A linear elastic model is the simplest one and it...
