This thesis presents the design of a new experimental technique for measuring the spatial and temporal pressure on a rigid target following detonation of a shallow buried explosive device: the Characterisation of Blast Loading (CoBL) apparatus. CoBL was designed to measure the output from a 6 kg TNT cylindrical charge at quarter scale, offering a balance between scientific validity and cost-effectiveness. In total, 91 experimental tests have been performed, which are reported and analysed in detail in this thesis.
Initially, a series of commissioning tests were performed to refine the experimental apparatus, increase the quality and accuracy of the data, and remove sources of error. Following this, a detailed parametric study was conducted to systematically investigate the influence of key parameters on the mechanism and magnitude of loading developed on the target surface, namely: charge encasement and shape; soil confinement and burial depth; soil saturation; particle size distribution of saturated soils; and standoff distance.
Experiments with modified charge cases provide an understanding of the interaction between the charge case and soil and the consequences of this interaction on the pressure-waveform. Two charge shapes were compared to investigate the focusing of detonation products for a spherical and cylindrical charge. Soil confinement and burial depth were investigated to assess the contribution of the confining media at the base, laterally and above the charge. Soil saturation was varied to investigate changes in response behaviour of the soil when the voids between soil particles become filled with water. Two saturated soils with particle size distributions described as ‘uniform’ and ‘well-graded’ were tested to compare the influence of the particle size distribution on the loading mechanism. Three standoffs were tested in partially saturated soil to investigate the evolution of the loading in ejected material.
The CoBL test apparatus has been used to produce the first detailed experimental study into the output from shallow buried charges with spatially and temporally resolved pressure histories measured above a shallow buried charge. The observations from these tests can be used to verify the behaviour of soils in numerical models allowing armour designers to accurately assess the mechanisms of loading applied to a protective structure when subjected to a buried IED attack.
