Abstract:

In order to assess the issues of personnel safety and building damage under the impact of tunnel blasting shockwaves, it is necessary to clarify the differences of the propagation characteristics of explosive air shockwaves between construction tunnels and traffic tunnels. A comparative analysis was carried out using the ANSYS/LS-DYNA software to observe the variations of shock wave propagation in single-end and two-way open tunnels. The factors such as the explosive location, the simultaneous detonation of multiple explosives and the blasting source explosive equivalent were investigated. The findings demonstrate that the blast shock wave propagation in the single-head tunnel undergoes a three-stage change pattern from three-dimensional spherical wave to one-dimensional plane wave gradually, and the boundary at the single-head tunnel's end constrains the initial spherical wave diffusion. Additionally, the results demonstrate that the overpressure caused by the wall reflection reaches 20%. The source's explosive equivalent has an impact on the wavefront change. The three-stage change mode of wavefront conversion position and explosive equivalent is a negatively correlated power function, and with the explosive equivalent increases, the conversion is closer to the source location. Multiple explosive sources lead to greater overpressure at near-field, but when it enters into the far-field one-dimensional plane wave propagation region, the influence of multiple explosive and explosive location on the wavefront destruction of characteristics of shock wave overpressure is limited. The relative error of overpressure is less than 5% when compared to the central detonation of a single source.

Key words: drill and blast tunnel, shock wave, propagation characteristics, source of explosion, simultaneous initiation of multiple blastholes, TNT equivalent charge weight