Numerical simulation on Time-dependent Behavior and Long-term Safety Analysis of Soft Rock Tunnel under Seepage Condition

Abstract

This study investigates the time-dependent behavior of soft surrounding rocks of the Shanxi Panxiushan railroad tunnel. Based on the viscoelastic-plastic damage mechanics, the rheological problem, mechanical properties of degradation, and seepage problem of the soft rock tunnel are comprehensively considered. The time-dependent deformation and stress of the surrounding rock mass following excavation were simulated using the proposed model of finite-difference software FLAC3D. The stress distribution of the surrounding rock support and reinforcement after the excavation were obtained. The simulation results show that the rationality of the existing reinforcement scheme is verified and the final deformation stability time of the surrounding rock during the operational period is calculated. Furthermore, a novel damage-based long-term safety analysis method is proposed, providing theoretical guidance and technical support for the design and construction of soft rock tunnels. The factor of safety (FOS) of the surrounding rock during the excavation and operational period is analyzed using the proposed analysis method. These results could have reference value for the design and construction of similar soft rock tunnels.