Elasto-plastic analysis of a multi-stage excavation in bonded geomaterials

School of Civil and Environmental Engineering, UNSW Sydney, NSW 2052, Australia

^* Corresponding author: h.moghaddasi.k@unsw.edu.au

Abstract

The deformation characteristics of braced and unbraced excavations in a dry structured soil are investigated numerically. A constitutive model based on the theory of bounding surface plasticity is used to predict the plastic deformation of the soil. A plastic cementation index is introduced in the hardening modules to capture soil degradation. In the model, the progress of the degradation is associated with the stress magnitude and the accumulated plastic deformation. The constitutive model is implemented in a finite difference code to analyse the lateral deformation of braced and unbraced excavations. The implemented model captures the strength increase of soils due to cementation, and predicts the subsequent debonding and strength degradation due to excavation. It is shown that soil cementation significantly influences the compression and tensile strengths of soils, and alters the deformation profile of the excavated face.