Longitudinal Displacement Profiles for Convergence Confinement Analysis of Tunnels in Elastic–Brittle–Plastic Rock Mass

This study investigates the construction method of longitudinal displacement profiles (LDPs) for elastic–brittle–plastic tunnel-surrounding rock using numerical simulation. First, an axisymmetric numerical model of a circular tunnel is established based on the physical–mechanical parameters of granite at 630 m depth, with customized model parameters covering varying ratios of in situ stress to the global strength of the rock mass. Second, tunnel excavation is simulated using an elastic–brittle–plastic model, yielding radial displacement evolution data at the excavation boundary as a function of distance from the tunnel face. A quantitative relationship between these displacements and distances is derived, forming the proposed LDP construction method. Third, the calculated displacement evolution data (using the proposed method) show high consistency with both simulated and field-monitored data, validating the proposed method’s accuracy and reliability. Finally, a set of LDPs for elastic–brittle–plastic tunnel-surrounding rock is established, enabling the efficient determination of optimal support timing and streamlined tunnel support design.