Large deformation finite element analyses in TBM tunnel excavation: CEL and auto-remeshing approach: Fid-Bau Portal

Large deformation finite element analyses in TBM tunnel excavation: CEL and auto-remeshing approach

Kim, Dohyun

Highlights • Theoretical basis and characteristics of two major large deformation analysis methods. • The implementation of the two methods in simulating TBM excavation and advance. • Evaluate the effect of TBM excavation on ground by estimating excavation damaged zone. • EDZ estimation by computation and comparison of two large deformation analysis methods.

Abstract Analyzing tunnel excavation behavior involves large deformation issues. For this reason, large deformation analysis method is required to rigorously investigate the actual effect of excavation on surrounding ground. Two major numerical approaches capable of considering large deformations are applied to investigating the effect of tunnel boring machine excavation: coupled Eulerian-Lagrangian (CEL) and the automatic remeshing after small strain approach. The theoretical basis and application of the methods will be discussed before their relative performance is evaluated through the ground response due to TBM excavation. The ground response will be quantified by estimating the range of the excavation damaged zone (EDZ). By comparing the results, the range of the size of the EDZ will be suggested along the vertical and horizontal direction along the TBM advancement. Based on the computed results, it was found that the size of EDZ around the excavation surface and the tendencies was in good agreement among the two methods. Numerical results clearly show that the size of the EDZ around the tunnel tends to be bigger for harder rocks. The size of the EDZ is found to be direct proportional to the tunnel diameter, whereas the depth of the tunnel is inversely proportional due to higher confinement stress around the excavation surface.