Investigation of blasting effects and mechanisms on concrete frustums under side-contact explosions

Abstract

Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations. This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions, employing both numerical simulations and field tests. It focuses on the effects of top and side blasting, with particular emphasis on fracture modes, damage patterns, and fragment sizes, as well as the causes of different failure modes and the propagation of stress waves. The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts. The results show that side-blasting leads to complete fragmentation, with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface, concentrating damage near the surface. During top-blasting, the upper half of the frustum undergoes fragmentation, while the lower half experiences cracking. Tensile waves propagate from the top to the bottom surface, forming larger blocks in regions with lower wave intensity. Three distinct damage zones within the frustum were identified, and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass. As the charge mass increased from 1.0 kg to 4.0 kg, the maximum fragment size decreased. Detonation at the center of the frustum's side resulted in the most severe fragmentation, with a 51.8% reduction in fragment size compared to other detonation positions. Finally, four broken modes were classified, each influenced by charge mass and explosive location. This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.