Numerical modeling of open TBM tunneling in stratified rock masses using a coupled FDM-DEM method

The complex engineering characteristics of stratified rock masses make the comprehensive analysis of TBM tunneling more complex and difficult. In this study, an advanced modeling method based on the coupled finite difference method (FDM) and discrete element method (DEM) was proposed for the simulation of open TBM tunneling in stratified rock masses. The modeling and analysis process of the FDM-DEM numerical model was presented with the DLS Tunnel as the research background. Numerical results show that the displacement values and characteristics of the rock mass are consistent with the deformation of the surrounding rocks obtained from in situ monitoring. Severe shear and tensile fractures occur progressively in both rock blocks and bedding planes during TBM tunneling. The extent of the loosening area in the rock mass also continues to grow. The numerical model reproduces the progressive failure process of the stratified rock mass through the analysis of contact fracture events and the evolution of contact forces. The simulation of the interaction between the rock mass and the shield is accomplished by FDM-DEM coupling methods under the large-strain mode. This study presents an effective tool for the comprehensive analysis of open TBM tunneling in stratified rock masses.