Dynamic behavior and response of rock and underground openings subjected to high initial stresses

The FEM and continuous damage mechanics-based numerical code RFPA is selected as the research tool. First of all, from the view of laboratory scale, numerical SHPB (split Hopkinson pressure bar) system is established to investigate the dynamic behavior of rocks under in-situ stresses. The derived results show that the dynamic compressive strength of rock increases with the increasing depth and parameter K which is defined as the ratio of horizontal stress to vertical one. Subsequently, from the view of rock engineering scale, dynamic response of underground openings under plane and cylindrical wave disturbances are numerically investigated. In the numerical model, the properties and distribution of rock joints are fully taken into consideration. The simulated results indicate that the additional attenuation of cylindrical waves occurs as the propagation distance increases in addition to the wave attenuation caused by rock and joint damage and wave reflection and transmission along joint surfaces. Moreover, it is found that the properties and distribution of joints directly determine the wave reflection and transmission along joint surfaces, which will further influence the damage degree and PPV (peak particle velocity) results of the underground openings.