Numerical Simulation and Application Research of Straight-Hole Cut Blasting with Empty Holes in Railway Tunnels

An empty hole in tunnel blasting and excavation serves as an auxiliary free surface and compensation space for blasting rocks, significantly influencing the blasting effects. The straight-hole cut blasting with an empty hole in a railway tunnel project was studied by theoretical analysis, numerical simulation, and field application. The influence law of two key technical parameters, the empty hole diameter and the distance between the cut and empty holes, on the blasting effect under the action of multihole blasting, was analyzed using ANSYS/LS-DYNA R11. The research results show that the final forming effect of the blasting cavity is closely related to the diameter of the empty hole and the distance between the cut and empty holes. When the empty hole diameter is twice the cut hole diameter, and the distance between them is 2.5 times the empty hole diameter, the cut blasting effect is the best. The blasting design and application of the straight-hole cut blasting with an empty hole on the site were carried out based on the theoretical analysis and numerical simulation results. The smooth tunnel after blasting, the average linear overexcavation value of about 9.3 cm, and the high contour-forming quality verified that the numerical simulation and blasting scheme was rational. The research findings can serve as a valuable reference for the blasting design of similar tunnel projects.