Simulation of Rock-Breaking Process by Drilling Machine and Dynamic Classification of Surrounding Rocks

Unfavorable geological phenomena such as fault development and weak surrounding rocks are the common challenges encountered in tunnel excavation. However, the conventional rock mass classification method is complex, and the data obtained through disturbed rock samples cannot be used to dynamically and accurately class the surrounding rock in real time. In this study, discrete element method (DEM) is applied to simulate the rock-breaking process by pneumatic rock drill, and the drilling parameters of the surrounding rocks with different classes including drilling rate, vibration acceleration, and vibration frequency, are acquired during the excavation. The simulation results are verified through the data obtained by field tests in Luoping tunnel and Zilinshan tunnel of the Sandu Expressway in Guizhou province, China. Furthermore, a standard database for the dynamic classification of surrounding rocks is established. The numerical simulations reveal a good correlation between the average drilling rate, vibration acceleration, and vibration frequency of drill bit and the class of surrounding rock, and these factors can be used as dynamic evaluation indices for advanced geological prediction during tunnel construction. Overall, the results can serve as a useful reference for advanced geological prediction and dynamic classification of surrounding rocks during the construction of tunnels.