Simulation of Stability and Support of High Stress Soft Rock Tunnel

In order to analyze the deformation characteristics and support effect of the high-stress soft rock tunnel, FLAC^3D software was adopted to simulate the stability and support measures of the soft surrounding rock of the deep buried water delivery tunnel of Central Yunnan Diversion Project. The displacement field, stress field and damage zone distribution of the surrounding rock under the conditions of the tunnel and support, as well as the stress state of the lining were calculated and analyzed, and the stability of the surrounding rock was evaluated. Reasonable timings for support are proposed. The results are as follows. The application of bolt-shotcrete support to deep soft rock can improve the confining pressure and bearing capacity of rock mass, and significantly reduce the deformation and damage degree of weak surrounding rock, but the deformation of surrounding rock is still large when only relying on bolt-shotcrete support. The greater the displacement release rate of surrounding rock when permanent lining is applied, the smaller the internal force of lining, but the greater the deformation of surrounding rock. Therefore, it is suggested to adopt full-section bolt-shotcrete support for high stress soft rock cavern to improve the rigidity and strength of the initial support. In addition, according to the internal force of the permanent lining and the deformation characteristics of the tunnel under the condition of different displacement release rate of surrounding rock, combined with the bearing capacity of the permanent lining and the clearance requirements of the tunnel, the appropriate time to apply the permanent lining can be determined.