Damage decoupled analysis of reinforced concrete slabs subjected to penetration and Explosion: Experimental and numerical investigation

To address the breaching requirements of reinforced concrete walls, this study analyzes the damage characteristics of reinforced concrete slabs (RCSs) subjected to penetration and explosion. Experiments were conducted using explosion of prefabricated hole and static explosion following penetration. Validated numerical models were employed to investigate the damage mechanisms induced by explosion shock waves and detonation gas. A decoupled approach was used to examine the damage capacities of cylindrical bare charges and the influences of pre-penetration damage on explosive performance. Results indicate that front surface damage primarily resulted from pressure crushing caused by shock waves and detonation gas, while rear surface damage arose from tensile failure due to stress wave reflection, superposition, and the shear plugging of detonation gas. Pre-penetration damage exerted a weakening effect on targets, thereby making cracks easier to form, and rendering cracks to extension during internal explosions. An optimal length-to-diameter ratio of 3.37, with constant charge mass, maximized damage to the RCSs under the studied conditions. Similarly, the highest damage occurred when the charge position-to-target thickness ratio was 0.50. The target dimensionless critical thickness for realizing effective hole expansion was set to 2.73. Perforation diameters after the explosion exhibited linear correlations with the dimensionless impact coefficient. Compared to the penetration at the rebar grid center, that at the midpoint of a single rebar and the intersection of rebars reduced the perforation diameter by 5.7% and 8.9%, respectively. The study offers practical guidance for optimizing charge design and placement, and informing breaching strategies through a deeper understanding of damage mechanisms and rebar configuration effects.