Stability Analysis and Support Optimization of Tunnel Surrounding Rock with Weak Interlayer Based on Catastrophe Theory

A tunnel excavation model with weak interlayers is established to analyze the effect of different angles and thicknesses on the displacement of the surrounding rock. Based on catastrophe theory, a stability criterion for surrounding rock displacement is derived, providing a theoretical framework for evaluating tunnel stability through numerical simulations. Finally, to minimize support construction costs, an optimization model is established by integrating the Particle Swarm Optimization (PSO) algorithm and the Radial Basis Function (RBF) neural network. The model is then validated through engineering projects. The results show that the deformation and stability of the surrounding rock are affected by the interlayer angle and thickness. As the angle increases, the maximum deformation of the surrounding rock gradually transitions from horizontal displacement to vertical displacement, while increased thickness amplifies deformation and concentrates it at the interlayer. The stability of the surrounding rock exhibits catastrophic characteristics, with instability often occurring in the middle and rear sections of the tunnel. Calculation costs are reduced by 88% using the PSO-RBF optimization model, and construction costs decreased by 34.96% after optimizing the support parameters. This study provides theoretical support for the stability analysis and construction optimization of tunnels with weak interlayers.