Failure mechanism and numerical simulation of zonal disintegration around a deep tunnel under high stress

The zonal disintegration phenomena in deep rock mass will appear with the increase of underground engineering depth which is widely different from shallow cavern. In order to reveal the formation mechanism of zonal disintegration, the geomechanical model test and numerical simulation of zonal disintegration are carried out respectively. Taking the deep tunnel of Dingji coal mine in China's Huainan coal mine as engineering background, a 3D geomechanical model test is carried out relying on the high stress 3D loading test system. The zonal disintegration phenomenon is observed, and the oscillation law of displacement and strain are measured. Based on the strain gradient theory and continuum damage mechanics, the zonal disintegration elastic damage-softening model is established. The relationship between rock failure and energy dissipation is analyzed. According to the strain energy density theory, the zonal disintegration energy damage failure criterion based on strain gradient is established. A numerical analysis method for zonal disintegration is proposed, the zonal disintegration calculation program is developed based on a commercial finite element code. The results of numerical simulation and the 3D geomechanical model test are basically consistent.