Abstract

Earthquakes may cause severe damage to engineering structures in the seismogenic fault zone. In near-fault regions, ground motions on the two sides of a fault exhibit significant asymmetry in terms of permanent displacement, velocity pulse, and dynamic displacement amplitude. Taking the Xianglu Mountain Tunnel in the southwest of China as the engineering object, this study designed scaled fault-crossing tunnel-surrounding rock test models and conducted a series of quasi-static and dynamic model tests using a dual-shaking table system with non-uniform ground motion input. The effects of three different earthquake action modes on the responses of tunnel engineering structures crossing seismogenic faults were investigated through five static and dynamic earthquake action modes. The test results indicate that considering only the dynamic effect of ground motion or only the static effect of permanent displacement due to fault dislocation will underestimate the seismic response and damage degree of the surrounding rock and tunnel structure. However, the contribution of dynamic effects of ground motion to tunnel failure is much smaller than that of static fault dislocation. The magnitude of permanent displacement from fault dislocation, the peak displacement of non-uniform ground motion time history, and the peak relative displacement are all important factors affecting the deformation of surrounding rock and the strain of tunnel structures. Traditional static analysis methods will lead to an underestimation of the damage risk of tunnel structures. Compared with the non-uniform earthquake action mode, the deformation within the fracture zone under the static action mode is underestimated by approximately 6.39%, and the peak tensile strain under the static action mode underestimates the damage risk by approximately 40%.

IPC Classification

Keywords