Hypoelastic-plastic-damage analysis of a tunnel in swelling rock mass

Abstract

In this study, we proposed a multi-stage analysis process to simulate the mechanical behaviour of a tunnel constructed in swelling rock mass, which including self-weight analysis, excavation analysis and swelling analysis. Especially, in the swelling analysis, a hypoelastic-plastic-damage model was constructed which can express the stiffness deterioration due to the damage that occurs with the process of rock swelling, and the plastic softening and hardening behaviour based on the Modified Cam-Clay (MCC) model. Furthermore, an implicit stress-update algorithm was formulated for the swelling model to obtain an accurate and robust numerical computation. A series of numerical examples of a tunnel in swelling rocks is shown in this study to discuss the mechanical behaviour of the tunnel due to the swelling of the bedrock, aimed at evaluating the stability of a tunnel constructed in swelling rocks after some years.