Research on Influence Zoning of Tunnel Side Crossing Existing Urban Roads Based on Ultimate shear strain Failure Criterion

At present, there are numerous examples of new tunnels crossing through existing urban roads. The stability of the new tunnel underneath the existing urban road is analyzed by strength reduction method. This thesis analyzes on the problems of the instability criterion of the different surrounding rocks at present, and the ultimate shear strain is selected as the criterion of instability of surrounding rock. By comparing the single tunnel with the adjacent system of the tunnel to the existing urban road, taking the difference of safety factor as the threshold value of the influence zone, the mechanical calculation models of different tunnels near the existing urban roads are established. Through the multi-factor analysis of the calculation results, the standard zoning diagram of the tunnels crossing the existing urban roads is obtained, which provides a reference for the similar projects in the future.