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Explosion craters on the ground surface induced by contact or near-field explosions have important implications, which can be used to assess blast consequences, guide the design of the explosion, or develop a protective strategy. In this study, to understand the crater characteristics induced by the contact explosion of large weight explosives, four field contact explosion tests were conducted on the surface of the Gobi Desert with large TNT charge weights of 1 ton, 3 tons, and 10 tons (test conducted twice). Cratering on the ground surface generated by large amounts of explosives was measured and evaluated, including the shape, depth, and diameter. A fine-mesh numerical model was developed and validated on the AUTODYN software platform, and a detailed parametric study was performed on the resulting craters. The effects of sand and gravel density, initiation method, shear modulus, and failure criteria were analyzed and discussed. An energy conversion coefficient was determined, and the corresponding theoretical equations were derived to predict the dimensions of the craters resulting from the large weight contact explosion. The calculated cratering characteristics were consistent with previous data and hence can be used in future engineering applications.

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Depleted uranium (DU) has surprising physical properties such as a high density, high hardness, and high toughness. A numerical method was developed in AUTODYN to study the penetration performance of a shaped charge with a liner made of DU with 0.75% titanium. By comparing different parameters and results from different models, the strength model suitable for DU was determined. According to available experimental data, the geometric strains in the strength models for DU and the steel target were calibrated. The characteristics of the DU liner, employed in a finished shaped charge instead of a copper liner, were optimized by tuning different parameters, and the performance of this optimal liner was verified through relevant tests. Moreover, in agreement with the optimized computational model and structural studies, a novel structure for the shaped charge was proposed that aimed to achieve a penetration depth of eight charge diameters. Different penetration depths were obtained by changing specific parameters, and the influence of standoff on the penetration depth was also studied. By evaluating the best penetration performance, the optimal structure for the shaped charge was finally determined. These results can have a great impact on future experimental tests and engineering applications of DU.

Lately, explosions with a large TNT equivalent have occurred with alarming frequency causing severe structural damage. The damage suffered by these structures has been exacerbated by the ground shock generated during these large equivalent explosions. The aim of this work is to study the ground-shock propagation behaviors, the areas affected by them, and determine the minimum safe distance for various structures. To measure ground shock data at different distances from the epicenter of the blast, actual 1 t and 10 t TNT surface explosion experiments were performed. The velocity and attenuation coefficient of the ground shock generated by the 1 t TNT surface explosion were determined, and the empirical equations provided by the UFC 3-340-01 standard were validated. Additionally, numerical analyses were performed to analyze the effects of ground shocks on buildings around an explosion. The maximum particle vibration velocities and attenuation behaviors of a 10 t TNT surface explosion as well as the minimum safe distances for a variety of structures were obtained from the numerical analyses.