Stability investigation of tunnel surrounding rock by coupling peridynamics, finite element method, and finite volume method

The construction environment of subsea tunnels is highly complex. Revealing the influencing factors and governing laws of surrounding rock stability as well as ensuring the stability of the surrounding rock during the construction process is crucial for the safe construction of the tunnel. Based on the coupling of peridynamics (PD) with finite element method (FEM) and finite volume method (FVM), the PD-FEM coupling method describes solid deformation and damage, while FVM solves the fluid seepage field. Data exchange is performed through a transition layer to achieve efficient fluid–solid coupling calculations. Using the Shantou Bay Subsea Tunnel as the engineering background, an engineering-scale simulation of the subsea tunnel excavation process was conducted. The results were validated by comparison with COMSOL simulation results and field monitoring data. Furthermore, 15 additional simulations were conducted. Through comparing and analyzing the distribution characteristics of excavation damage zones, displacement fields, and seepage fields in the surrounding rock under various influencing factors, this study unveils the influence patterns of tunnel burial depth (in situ stress conditions), seawater depth (groundwater pressure), rock mass elastic modulus (surrounding rock properties), and tunnel excavation methods on the stability of surrounding rock in Shantou Bay Subsea Tunnel. This provides a scientific basis for predicting the stability of subsea tunnel surrounding rock and ensuring safe construction.