A COMPUTATIONAL ANALYSIS OF DETONATION OF BURIED MINES

A nonlinear-dynamics transient computational analysis of the explosion phenomena associated with detonation of 100g of C4 high-energy explosive buried at different depths in sand is carried out using the AUTODYN computer program. The results obtained are compared with the corresponding experimental results obtained in Ref. [1]. To validate the computational procedure and the materials constitutive models used in the present work, a number of detonation-related phenomena such as the temporal evolutions of the shape and size of the over-burden sand bubbles and of the detonation-products gas clouds, the temporal evolutions of the side-on pressures in the sand and in air, etc. are determined and compared with their experimental counterparts. The results obtained suggest that the agreement between the computational and the experimental results is reasonable at short post-detonation times. At longer post-detonation times, on the other hand, the agreement is less satisfactory primarily with respect to the size and shape of the sand crater, i.e. with respect to the volume of the sand ejected during explosion. It is argued that the observed discrepancy is, at least partly, the result of an inadequacy of the generic materials constitutive model for the sand which does not explicitly include the important effects of the sand particle size and the particle size distribution, as well as the effects of moisture-level controlled inter-particle friction and cohesion. It is further shown that by a relatively small adjustment of the present materials model for sand to include the potential effect of moisture on inter-particle friction can yield a significantly improved agreement between the computed and the experimentally determined sand crater shapes and sizes.