Experimental and numerical investigation of the damage effects in an underwater confined box subjected to internal blast loading

To investigate the effects of an internal explosion on the damage characteristics of an underwater box structure, the internal blast load characteristics and damage effects on an underwater thin-walled closed steel box are investigated via underwater internal explosion tests and numerical simulation methods. The main conclusions are as follows: (1) When the explosive detonates inside an underwater thin-walled confined steel box, the shock wave undergoes multiple reciprocal reflections, superposition, and convergence on the wall surface. The pressure exhibits characteristics such as multiple peaks and a long positive pressure action time. (2) When the radius of the bubble generated by the explosive is larger than the distance between the explosive and the box wall, the damage to the box caused by the internal blast is due to the bubble expansion load, with the shock wave load in the water playing a supplementary role. (3) The damage modes of an underwater thin-walled water-filled box under the action of an internal explosion include four main types: plastic deformation, angular tearing, corner cracking, and entire plate shearing. (4) The degree of damage to the steel box intensifies as the charge increases and decreases correspondingly as the wall thickness increases.