Dynamic response and progressive damage modes of fault-crossing tunnels simulated using similar materials

Abstract

Tunnels are widely constructed because they can effectively withstand seismic loads and avoid tunnel collapse in high-intensity seismic zones. However, in the case of fault-crossing tunnel, the fault crossing tunnel will be seriously damaged in seismic activities because the tunnel lining follows the deformation of surrounding rock. Therefore, the researches of the dynamic response and failure modes of fault-crossing tunnel are highly significant. In this study, quartz sand, cement and detergent were used to simulate similar materials of surrounding rock. A gypsum-based materials have been selected as similar materials for tunnels. The shaking table model tests were conducted on fault-crossing tunnel and conventional tunnel based on the Xianglushan Tunnel. The dynamic response characteristics of the fault-crossing tunnel were analyzed, and draw the conclusions: The acceleration amplification coefficients of the two sets of tests exceeded 1. The acceleration dynamic response of the fault-crossing tunnel was greater than the conventional tunnel, and the acceleration dynamic response at the fault was greater than the monitoring surface on both sides, rendering the acceleration dynamic response at the fault abrupt. Compared to other cross sections, tunnel lining structures at faults had the strongest dynamic response. The maximum peak strain value of the fault-crossing tunnel was magnified 4.4 times, and the bending moment value was magnified 2.3 times, relative to those of the conventional tunnel. The fault markedly increased the strain peak and bending moment values, causing cracks and damage even at a small peak acceleration value, weakening the seismic capacity of the tunnel. The lining at the fault was dominated by longitudinal cracks, and dislocation occurred. The degree of destruction and development of tunnel at faults was greater than that of other cross sections. The research results and conclusions could provide a reference to prevent the destruction of fault-crossing tunnel in an earthquake.