Effect of Water Table Position on the Stability of Tunnel

Abstract

Tunnel is an underground structure used to convey the traffic. Construction of a tunnel in rock is a difficult task. In instances where tunnels are situated at shallow depths, the stability of the tunnel and its lining is notably affected by the adjacent surcharge loadings resulting from new building constructions or excessive loads on the ground surface. Stability of the tunnel crest also depends on the position of the water table. This study shows the effect of the water table position on the displacement behavior of tunnel at the tunnel crest. The assumption in this study is that the rock mass is homogeneous and isotropic. Three distinct positions of the water table are taken into consideration. . A shallow circular tunnel with a thick lining of concrete is analyzed with the help of numerical simulation.
The utilization of numerical simulation has become prevalent in predicting rock mass convergence during tunnel excavation. Employing numerical analysis in tunnel design serves to mitigate fractures and failures across various tunnel types, effectively managing and minimizing the risks associated with tunnel construction. The analysis in this context utilizes the FLAC3D finite difference software package. From the numerical study, it is observed that the position of the water table affects the displacement behavior of the tunnel. The tunnel crest experiences the maximum displacement when the water table encounters the tunnel crest.