Finite element analysis of braced excavation in nonuniform soils

Abstract

Numerous studies have been carried out for braced excavations in sand or soft/stiff clays individually, but there are limited studies on nonuniform soils consisting of soft clay over-lying a stiff clay layer. The study of the effects of various parameters, such as the thickness of the soft clay layer, stiffness of the wall system and the number of strut levels, on the strut forces, maximum ground settlement behind the wall, and the maximum wall deflection are investigated using the finite element analysis software, Plaxis 2D. The Hardening-Soil model was used to model the stress-strain behaviour of the soils.

The finite element results indicate that the maximum wall deflection increases with increas-ing depth of excavation. The wall deflection increases with a decrease in the stiffness of the wall, a decrease in undrained shear strength of the soft clay and an increase in the width of excavation. The ground settlement decreases with increasing distance from the wall. The result indicate that the maximum ground settlement increases as wall stiffness decreases, an increase in the excavation width and a decrease in the undrained shear strength of the soft clay. An increase in excavation width and a decrease in undrained shear strength of the soft clay causes an increase in maximum strut force.