NUMERICAL SIMULATION OF ROCKBURST STRESS STATE DURING EXCAVATION OF UNDERGROUND POWERHOUSE OF PUBUGOU HYDROPOWER STATION

The underground powerhouse of Pubugou Hydropower Station is located in the complex geological environments.Rockburst happens frequently during the excavation of powerhouse.The initial stress and its computing method are studied to analyze the effect of surrounding rock stress on rockburst.The linear regression is adopted to test the geostress of powerhouse.The loading of initial geostress is accomplished in ANSYS;and the initial geostress field close to the actually measured one is obtained.3D finite element numerical simulation is conducted for the excavation of underground powerhouse.According to the rockburst discrimination criteria,the dangerous region where rockburst is apt to happen is predicted;and the dangerous degree is classified.The prediction result of rockburst almost accords with the monitoring one in field.The study results show that the geostress of the underground powerhouse in the Pubugou Hydropower Station is prominent and has stronger directional property.The surrounding rock in the underground powerhouse is stable in the whole.High-level rockburst is easy to happen at the arch springing and intersection of caverns.