Three-dimensional numerical modelling for TBM tunnelling in consolidated clay

Abstract

This paper presents a new field to analyze three-dimensional (3-D) coupled linear flow for Tunnel Boring Machine (TBM) tunnelling in saturated porous medium. This is important to control ground deformation and excess pore water pressure due to the process of shield tunnelling in three-dimension and time-dependent. A numerical model to simulate explicitly the behaviour of excess pore water pressure mobilization and its dissipation in time is presented. For the TBM tunnelling techniques, the positive pressure is applied to support the tunnel face and the grouting material is injected to decrease the deformation into the tail void gap behind the shield. Hence, this study is employed on 3-D model to investigate the impact of the most important parameters, which are slurry pressure and grouting pressure. The governing equations are derived in the light of the generalized Biot theory where displacement and excess pore pressure are the primary unknowns. The excavation stages during the advance of the machine in 3-D consolidation analysis is simulated. An isoparametric quadratic solid consolidation elastic soil model is used for this analysis. Results of this study indicate that a realistic modelling of soil behaviour, especially the distribution shape of the excess pore water pressure around the TBM tunnels during the construction stages and its dissipation during the consolidation time can be assessed. Thus, short-term as well as long-term effects of the TBM tunnelling are predicted. The practical importance of this analysis is the optimization of values and quantities of the slurry pressure and grouting pressure required for TBM technology. A design criterion based on this study can be suggested to tunnelling procedure in consolidated clay.