Explore Propagation and Reflection Characteristics of Tunnel-Blasting Seismic Waves in Rock Mass with a 3D Structure-Geology Model

The advanced geological forecasting method in a tunnel is to determines abnormal geological structures ahead of the excavation face and provides guidance for the construction and the early alert of sudden geological disasters. Utilizing seismic wave reflection is an implementation for advanced geological forecasting, which generally excites seismic waves by explosives and receives signals from sensors placed in the surrounding rock. However, most research ignores the mechanical processes of blasting and directly uses the Reckoner wave function as a point source. As regards the complex explosion mechanism and rock mass, the study aims to explore the propagation and reflection of blasting waves in the rock mass around the tunnel. First of all, an infinitely large soil model with spherical charge blasting is established based on LS-DYNA, and numerical results are compared with the analytical solution to verify the accuracy and validity of the numerical simulation. Then, the 3D structure-geology tunnel model is built, and the explosion and blasting-wave propagation are simulated. After that, an analysis is conducted on the propagation law of blasting stress waves and the change in vibration velocity of the surrounding rock when there is a reflective boundary and no reflective boundary in front. In conclusion, this research contributes to advancing tunnel geological forecasting by considering the mechanical processes associated with blasting and investigating the behavior of blasting waves in the rock mass. This offers the potential for utilizing seismic waves generated by tunnel blasting directly for geological exploration purposes.