Impulse loading resulting from shallow buried explosives in water-saturated sand

Abstract

A transient non-linear dynamics analysis of the detonation of a landmine buried to different depths in water-saturated sand is carried out in order to determine the resulting impulse loading. The results obtained are compared with their experimental counterparts obtained using the vertical impulse measurement fixture (VIMF), a structural mechanical device that enables direct experimental determination of the blast-loading impulse. The mechanical response of the structural steel used in the construction of the VIMF and the hydrodynamic response of the TNT high-energy high-pressure detonation products generated during detonation of a mine and of the air surrounding the VIMF are represented using the standard materials models available in the literature. The mechanical response of the sand surrounding the mine, on the other hand, is represented using the present authors' recent modified compaction model [1], which incorporates the effects of degree of saturation and the rate of deformation, two important effects, that are generally neglected in standard constitutive models for sand. The results obtained indicate that the use of the modified compaction model yields a substantially better agreement with the experimentally determined impulse loads over the use the original compaction model. Furthermore, the results suggest that, in the case of fully saturated sand, the blast loading is of a bubble type rather than of a shock type, i.e. it resembles under-water explosion.