Effect of Blasting Process of Drilling and Blasting Method on Stability of Composite Support Structure in High Ground Stress Tunnel

Abstract

The structural response of blast vibration to composite supports in deep-buried tunnels is an extremely complex research problem. At present, most of the studies and field experiments are based on single support with blast vibration as the main research direction. However, nowadays, it is difficult for single support to meet the existing construction requirements, and the impact of blasting vibration on the composite support structure is studied in a shallow breadth and depth due to its many influencing factors. Taking the Leshan Grand Canyon tunnel excavated by drilling and blasting method as an example, this paper studies the impact of blasting load on composite support structure lining under a high-ground stress environment through LS-DYNA numerical simulation and draws the following conclusions. The analysis was mainly focused on the vibration speed, displacement, and stress situation of the initial support. It can be seen that the vibration speed on the initial support is within a reasonable range, and the displacement is in a small range, with a maximum displacement of only about 0.88 mm. However, the tensile stress on the initial support is relatively high, with the maximum reaching around 12 MPa, which may cause damage. The stress far away from the face of the tunnel decreases accordingly. According to the numerical simulation results, due to the simplified model, the error in the results is biased toward danger. However, overall, the simulation results are more complex with the actual predictions, and the results are more reliable.