Numerical modeling of the effects of ground fissure dislocation on metro tunnel

Abstract

The formation of ground fissures is caused by tectonization activities such as earthquake or by human engineering activities such as excessive pumping of underground water. The latter has become a major cause of ground fissures formation in Xi’an, China. These ground fissures are still active and has become an obstacle for metro construction. In this paper, Xi’an metro line 3 was taken as a practical example to analyze the dislocating effects on shallow buried tunnels. The method proposed in Chinese tunnel design code was employed to evaluate the safety of tunnel liner and was implemented by using the programming language embedded within FLAC3D. The results show that tunnel passing crossing ground fissures cannot serve well without multiple deformation joints and that the failure scopes of the tunnel liner are approximately 23 m in the case. In addition, an engineering countermeasure was proposed to mitigate the dislocating effects on tunnel.