Dynamic response analysis on the slotting hole blasting in rock tunnels and comparative study on simulation methods

The quality of tunnel excavation using the drilling and blasting method is directly related to the construction cost of the project, and over-excavation and under-excavation have always been difficult problems to solve during the tunnel excavation process. This paper adopts numerical simulation methods and relies on the physical and mechanical performance parameters of the surrounding rock in the rock strata of the Zhongliangshan Tunnel on the Chongqing Wuhan Expressway to systematically study the differences in dynamic response between slotted holes and conventional circular hole blasting in the rock mass. The focus is on analyzing the stress distribution, crack propagation law, and simulation accuracy of different algorithms. The results showed the following: (1) The slotted hole exhibited a significant stress concentration effect at the tip of the slot, with a peak pressure increase of 20.85% compared to the circular hole. The crack propagation speed along the slotted direction was three times that along the non-slotted direction. (2) In the two-dimensional model, the residual of the ALE algorithm is only 0.074 GPa, which is better than that of the SPH algorithm (residual −1.015 GPa), but SPH has more advantages in three-dimensional dynamic crack visualization. The research results provide theoretical support for the optimization design of the drilling and blasting excavation plan for the Zhongliangshan Tunnel on the Chongqing Wuhan Expressway.