Analysis of Stress Evolution Characteristics of Surrounding Rock in Deep-buried Tunnels Crossing Fault Zone

The frequent geological movements lead to the widespread development of fault zones, which will wreak havoc on the safety of deep tunneling. To ensure the safety and efficiency of tunnel construction, accurately depicting three-dimensional (3D) stress response characteristics of rock masses affected by excavating deep-buried tunnels crossing fault zones is a key scientific issue that should be urgently addressed. The finite difference software FLAC3D was used in this study to simulate the excavation process of Xianglushan Tunnel which crosses the fault zone, and then, the 3D stress evolution characteristics and damage pattern of surrounding rock were further discussed. The consequences indicate that: there is a rotation phenomenon of principal stress axes during the tunneling process, and the disturbance range of soft rock is larger than that of hard rock; the stress disturbance index of surrounding rock (SDIsk) proposed in this study can reflect three phenomena occurring in surrounding rocks, comprising stress concentration, stress release and rotation of principal stress axes; the detrimental effects of tunnel buried depth should be concerned while excavating the tunnels crossing fault zones. It is anticipated that relevant knowledge and conclusions will provide the guiding significance for analyzing other similar tunnel excavations under the condition of large buried depth.