Deformation characteristics and failure mechanism of surrounding rock of high-stress large-diameter cylindrical caverns

Aiming at the deformation and damage phenomena such as rock burst, spray layer cracking and steel strand ejection in high-stress large-diameter cylindrical caverns, the development and evolution process of deformation and damage of the surrounding rock is explained through field investigation, observation of displacement of rock mass and stress of anchor cable. The internal fracture characteristics of the surrounding rock are observed through borehole camera, and the evolution mode of the deformation and failure of the surrounding rock is summarized. The deformation and failure mechanism of the surrounding rock of the cavern is revealed through numerical simulation, and reasonable support suggestions are put forward. The deformation and failure of the high-stress large-diameter cylindrical caverns is a chain-driven disaster process. The internal cracking of the surrounding rock leads to the increase in the displacement of the rock mass and the load of anchor cable. The steel strands break and pop out when the load of anchor cable exceed the limit. The surrounding rock and sprayed layer of unconstrained cave wall bulge and crack under the action of unloading. The high initial ground stress and the stress concentration induced after excavation, the low crack initiation strength of basalt, the superposition of stress induced by excavation adjacent to the cavern, and the weak support strength in the stress concentration areas lead to the occurrence of internal cracking in the surrounding rock. Setting enough pre-stressed long anchor cables and reasonable tension force in the stress concentration areas of the surrounding rock of the cavern can effectively reduce the depth and degree of internal fracture of the surrounding rock.