CHAPTER 6

FINITE ELEMENT ANALYSIS

6.1 Introduction

In this study, finite element analyses were carried out to investigate the behaviour of deep excavation. As mentioned in the literature review (Chapter 2), the finite element method (FEM) have been extensively used in the design of excavation to estimate the deformation and bending moment in the retaining structure and also to assess the effects of excavation on nearby buildings. However, there are several shortcomings in many existing FEM analyses which are unable to predict the ground movement successfully, especially for surface settlement far from the excavation (Tan et al., 1995). This is due to the soil model and soil parameters obtained from standard testing methods being unable to accurately simulate the real soil conditions. One of the shortcomings may be due to the under estimation of soil stiffness in the small strain stage as reported by Simpson et al. (1979), Jardine et al. (1986), Burland (1989) and Simpson (1992). However, to date, there is still not much experimental data on deep excavation to further support this idea. This chapter is aimed to gain a better understanding on the effect of soil model and boundary condition on deep excavation. The feasibility of numerical modelling is evaluated by comparing it with centrifuge tests. However, no numerical evaluation of the stiffness at small strain is included in this study.