Propagation characteristics of stress wave in layered rock mass under the impact of high-pressure gas

As a highly safe and environment-friendly blasting technology, high-pressure gas blasting has replaced traditional explosive blasting in some engineering fields. This paper focuses on the characteristics of high-pressure gas impact load and the propagation law of the stress wave in layered rock mass under high-pressure gas blasting by experimental and numerical simulation methods. Firstly, through the experimental test of hole wall pressure, a segmented exponential model of the hole wall pressure under the impact of high-pressure gas is proposed, which can accurately account for the time history characteristics of hole wall load under the impact of high-pressure gas. Next, the experimental test of stress wave propagation is carried out, and the results show that the interface of soft rock and hard rock has a significant effect on the stress wave propagation in the layered rock mass. Based on the experimental test results, a specific strain model under 10 MPa high-pressure gas impact is fitted for single-hole layered rock mass, and a polynomial exponential model form is put forward and a specific strain model under 20 MPa high-pressure gas impact is fitted for the double-hole layered rock mass, which can well characterize the attenuation law of the stress wave for single-hole and double-hole layered rock mass respectively. The propagation characteristics of stress wave in layered rock mass under the impact of high-pressure gas are preliminary analyzed. Finally, a same numerical model consistent with the experimental test of stress wave propagation is established. The numerical model adopts the RHT material model with the tested parameters, and the proposed segmented exponential models of hole wall pressure are applied to the lower, middle and upper parts of the blasthole respectively. After the feasibility of the numerical model is analyzed, the propagation characteristics of the stress wave are further studied based on a specific underground pipe gallery project by numerical simulation. This study has important theoretical guiding significance and practical value for improving the rock breaking theory and optimizing the construction scheme of high-pressure gas blasting in layered rock mass.