Stability analysis of underground surrounding rock mass based on block theory

Evaluation of the performance of existing support in underground tunnels is of great importance for production and interests. Based on field investigation, the shape and number of joints and fractures were investigated in the mining area. Then, the stability of each structural blocks is analyzed by 3D wedge stability analysis software (Unwedge). Moreover, a new analysis method based on critical block theory is applied to analyze the stability of excavated laneways in continuous and discontinuous rock and monitor the stress changes in a fractured tunnel rock mass. The test results indicate that the 3D wedge stability analysis software for underground excavation can evaluate deep tunnel support. Besides, there is no direct relation between the size of the block and the instability of the tunnel. The support method, on large and thick key blocks, needs to be improved. In a broken tunnel section, U-shaped steel support can effectively promote the stress state of the surrounding rock. By monitoring the surrounding rock, it is proven that the vibrating string anchor stress monitoring system is an efficient and real-time method for tunnel stability evaluation.