Characterisation of buried blast loading.

While it is well known that detonation of shallow-buried high explosive charges generally results in above-surface loading which is greatly amplified compared with the same detonation in air, uncertainty persists as to the mechanisms leading to this effect. The work presented in this paper is a systematic investigation into the mechanisms of load transfer in buried blast events. This paper details the results from a parametric study into the mechanisms and magnitudes of load transfer following a shallow-buried explosion, where spatial and temporal load distributions are directly measured on a rigid surface using an array of Hopkinson pressure bars. In particular, the investigation has looked at the influence of both geometrical confinement and geotechnical conditions on the loading. The parametric study was separated into four main threads: the influence of physical confinement; gravimetric moisture content; stand-off distance and depth of burial; and soil material/particle size distribution. This study allows a direct observation of the contributions of each of these distinct parameters, and in particular the ability to discern how each parameter influences the temporal form and spatial distribution of the loading.

Response of hybrid III and Mil-Lx ATD legs to explosively driven vehicle floor loading.

Results are reported of small-scale explosive experiments with Hybrid III and Mil-Lx anthropomorphic test device (ATD) legs. The legs were subject to loadings from deforming metallic plates, driven by explosive loadings to replicate the movement of the floor of a protected vehicle subject to a land-mine strike. The forces measured by the legs are reported and compared between the two different leg types. The benefits of protective measures, including false-floors and commercially available footpads, are compared for their ability to reduce the forces measured in each leg type. It is concluded that the two leg types respond differently to different protective measures and hence cannot be used interchangeably.

Blast Quantification Using Hopkinson Pressure Bars.

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures up to many hundreds of megapascals. In this respect the simplicity of the Hopkinson pressure bar has a major advantage in that while the measurement end of the Hopkinson bar can endure and be exposed to harsh conditions, the strain gauge mounted to the bar can be affixed some distance away. This allows protective housings to be utilized which protect the strain gauge but do not interfere with the measurement acquisition. The use of an array of pressure bars allows the pressure-time histories at discrete known points to be measured. This article also describes the interpolation routine used to derive pressure-time histories at un-instrumented locations on the plane of interest. Currently the technique has been used to measure loading from high explosives in free air and buried shallowly in various soils.