Numerical analysis on zone-divided deep excavation in soft clays using a new small strain elasto–plastic constitutive model

Abstract

Accurate prediction of displacements associated with deep excavations is essential to ensure safety and stability of the excavation and to prevent any damage and distress to the adjoining infrastructures. This paper presents a numerical approach for prediction of ground displacements related to a zone-divided deep excavation construction executed in Shanghai soft clays based on a new elasto–plastic constitutive model (small-strain Shanghai model) that incorporates small strain stiffness. This model can describe the mechanical properties and structural and over-consolidated characteristics of natural clays. The model is implemented into a finite element analysis software. Numerical analysis on the deep excavation in Shanghai using zone-divided method is conducted. A comparison between monitored and simulated results of horizontal displacements along the diaphragm wall, the settlements in the surroundings, and the effects on the adjoining metro tunnel due to excavation construction is carried out. Special attention is paid to the stiffness degradation of representative elements in the ground. The simulated displacements show a good agreement with the monitored data. Overall, this study provides an integrated solution for predicting displacements related to deep excavation in soft clays.