Quantitative analysis of rockburst in the surrounding rock masses around deep tunnels

Rockbursts in deep tunnels subjected to high crustal stress were investigated using a general particle dynamics (GPD) code with the Holmquist-Johnson-Cook damage model (HJC). Under dynamic excavation disturbance, several numerical tests were carried out to investigate the dynamic failure patterns of surrounding rock masses with different preexisting cracks around deep tunnels. The numerical results showed that the GPD code can satisfactorily simulate the phenomenon of rockburst caused by crack evolution, including predicting the ejection velocity, rockburst location and ejected rock block volume. Moreover, the analysis of the circumferential stress in the surrounding rock of deep tunnels at the Jinping II Hydropower Station shows the efficiency of the GPD code. In addition, four typical rockburst, which occurred under different geological conditions at the Jinping II Hydropower Station, were analyzed by using the GPD code. The numerical simulations suggested that the GPD code can efficiently reproduce the 2D and 3D crack growth in the surrounding rock, which eventually leads to the occurrence of rockburst.