Study on the Propagation Law and Waveform Characteristics of a Blasting Shock Wave in a Highway Tunnel with the Bench Method

In the bench method of tunnel excavation, the blasting impact from upper bench blasting poses significant risks to personnel and equipment. This study employed dynamic analysis software, ANSYS/LS-DYNA, and field testing to examine the propagation characteristics and attenuation behavior of tunnel shock waves. The findings revealed that, near the central axis of the tunnel, shock wave overpressure was lower compared to areas near the tunnel wall due to reflections from the wall. As the shock wave traveled a distance six times the tunnel diameter, it transitioned from a spherical wave to a plane wave. The attenuation coefficient for the plane wave ranged from 1.03 to 1.17. A fitting formula for shock wave overpressure attenuation, based on field test results, was proposed, and it showed good agreement with the numerical simulation results. This provided valuable theoretical insights for predicting shock wave overpressure during bench method tunnel excavation.