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 pswith respect to height. Shock pressure ps(H) in an underground structure exit can scale the strength of the blast wave on the ground.
numerical simulation, subsurface magazine, mitigation, blast wave