Estimation of the Excavation Damaged Zone (EDZ) around TBM Tunnel using Large Deformation Analysis

This paper aims to estimate the distribution and magnitude of the excavation damaged zone (EDZ) caused by the tunnel boring machine (TBM) through dynamic three-dimensional large deformation finite element analysis. Coupled EulerianLagrangian (CEL) analysis was used to consider the large deformation behavior during TBM excavation. The analysis model was verified based on estimations reported in the literature and experiment data. The apparent magnitude of the EDZ will be suggested as a boundary under various conditions, normalized by tunnel diameter (D). Based on the numerical results, the apparent magnitude of the EDZ was shown to be in the range of 0.2D – 0.4D for most cases, in front, upper and lower zone of the tunnel. Additionally, a parametric study was performed by controlling the rock type, tunnel diameter and tunnel depth. Through parametric studies it was found that as the rock mass rating (RMR) gets lower, the EDZ around the tunnel tends to decrease. The magnitude of the EDZ was found to be proportional to the tunnel diameter, whereas the depth of the tunnel were inversely proportional to the magnitude of the EDZ.