Explosion morphology and impacting effects of shallow-buried explosives

In modern warfare, shallow-buried explosives, such as landmines and improvised explosive devices, pose serious threats to civil/military vehicles and passengers. To study the explosion morphology and impacting effects of shallow-buried explosives (TNT), a novel set of test facility was proposed in this study and used to perform shallow-buried sand explosion tests. By changing the type of sand and the buried depth of the explosives, the propagation of shock wave, the ejection trajectory of explosion products and sand, the deformation morphology of target plate, and the spatial distribution of explosion load were systematically investigated. It was demonstrated that shallow-buried sand explosion generated a shock wave in air, with a propagation velocity significantly greater than the ejection velocity of explosion products and sand. Upon detonation, the explosion products and sand were rapidly ejected outwards with continuously increasing volume, and spread around after hitting the target plate. The impulse generated by shallow-buried sand explosion was non-uniformly distributed in space, largest in the central explosion area and gradually decreasing outwards. The buried depth of explosives in sand affected the relative position of explosive products and sand when they were ejected. When the buried depth was relatively small, the explosive products would break through the covered sand layer and directly act on the target plate. When the buried depth was sufficiently large, the explosive products were essentially covered by a sand layer, which acted on the target plate together at a delayed instant. The type of sand used significantly affected the deformation morphology of the target plate. The sand purposely prepared in accordance with the NATO standard AEP-55 not only caused overall bending deformation of the target plate, but also formed a large number of pits on the target plate, thus generating a penetration effect. In contrast, the ordinary river sand only caused overall bending deformation of the target plate, with little penetration effect observed. The results obtained in this study are helpful for designing more effective protective structures against intense blast impacting from shallow-buried explosives.