Numerical estimation of blast wave strength from an underground structure

This paper shows the propagation phenomenon of a blast wave from an explosion originating inside an underground structure. We numerically and theoretically estimate the blast wave strength from the simplest two-dimensional axisymmetric underground structure in order to discuss mitigation effects on a blast wave on the ground from the structural advantage. Height H and diameter D of the underground structure are the parameters used in this study. A small height H does not show any mitigation effect on a blast wave on the ground at a distance far from the underground structure. When H is larger than critical height H*, depending on D, the peak overpressures on the ground are mitigated, and the increment of H has a far greater mitigation effect. The shock pressure inside the underground structure is estimated by the one-dimensional shock tube problem, which determines critical height H* and shock pressure distribution p(s) with respect to height. Shock pressure P-s (H) in an underground structure exit can scale the strength of the blast wave on the ground.