Numerical simulation of a deep excavation in London Clay

摘要

The requirement for accurate modelling of the small-strain stiffness behaviour of soils in numerical analysis has been driven by the need to establish serviceability limit states for geotechnical structures. A common approach when tackling this problem is to employ a non-linear elastic constitutive model coupled with an appropriate failure criterion. The latter establishes the shear strength of the material and allows the evaluation of plastic deformations at large strains, while the former typically reproduces the effect of stress and strain levels on the shear and bulk stiffness of the soil. This paper evaluates distinct strategies for reproducing the stiffness of a material within the context of a new small-strain stiffness model. After introducing the constitutive model and describing its key features, a procedure to determine its parameters is proposed and demonstrated for London Clay. Subsequently, the relative impact of the different methods of interpreting the effect of changes in strain path direction on the stiffness of the material is investigated by performing finite element analyses of a deep excavation in London Clay.