Numerical Experiment Of Failure Process Of Jointed Rock Mass Under Dynamic Loading

In recent years, with the improvement of the scientific and technology and the needs of the social development, the development and utilization of underground engineering has become one of the focus areas around us. In nature, earthquakes, blasting occurred frequently. Therefore, research on the stability of underground engineering under dynamic loading such as earthquake, blasting is very important. There are rock joints, micro cracks and holes and other defects in rocks. Mechanical properties and failure mechanism of rock mass under dynamic loading is very important. In practical engineering, when tunnel crossed the jointed rock mass, sliding, collapse or gushing occurred frequently, which would cause serious damage to the stability of tunnel, therefore it’s necessary to study the influence of the joints.Based on the finite element stress analysis and the microscopic damage mechanics, numerical code RFPA is adopted to simulate the process of fragmentation of jointed rock mass and the stability of the tunnel under dynamic loading in different conditions. The research contains the following parts:(1) Numerical code RFPA is adopted to simulate the failure process of jointed rock mass subjected to dynamic loading. The failure characteristics of jointed rock mass with different number of joints, different joint discontinuity degree and different joint dip angle under different amplitudes of stress wave are studied respectively. The numerical results show that the failure process and failure extent of intermittent jointed rock mass is closely related to the parameters of joints and amplitudes of stress wave.(2) The damage of rock mass with different joint discontinuity degrees is compared with the Split Hopkinson Pressure Bar test. This method is proved reasonable and reliable by the similar conclusion.(3) Build up the model and simulate the jointed rock tunnel’s stability. The failure characteristics of different distance between joint and tunnel, different number of joints, different joint discontinuity degrees are studied respectively. When the joint goes through the tunnel, the specimen is destroyed the most serious. With the increase in the distance between joint and tunnel, the tunnel becomes more and more stable; The more the number of joints, the larger of the displacement and the plastic zone of rock around tunnel, and less stable the tunnel is; When the total length of joint is certain, scattered joints are more destructive than long joints.(4) The stability of the tunnel in the rock mass under dynamic loading is simulated. The position of joints and its interaction with the tunnels are studied. It shows that the position of joints and interaction with tunnels aggravate the damage of tunnels. Finally, the damage process of tunnel under dynamic and static loading is compared and analyzed.