Secondary damage of RC slabs under contact explosions of array charges: Mechanism and failure model

Abstract Array charges significantly enhance the damage efficiency against RC slabs under equal‐mass conditions, which is primarily attributed to secondary damage induced by the collision and coupling of detonation products in inter‐charge gaps. Based on mass and momentum conservation and the incompressibility assumption of target slabs, a secondary damage theoretical model is developed. The gap interaction domain is categorized into three functional zones with analytical impulse formulas derived, and a momentum‐based penetration criterion for pre‐damaged slabs is proposed. 52 numerical cases with varied charge heights and spacings are systematically analyzed, and a dimensionless pressure prediction equation is formulated via dimensional analysis. This model provides effective guidance for determining the minimum charge required for RC wall breaching in engineering practice. Numerical simulations indicate that the proposed criterion can reasonably predict the critical penetration spacing when H/B ≥ 0.22. The 2 × 2 array charge tests correctly verified the model's prediction of the target slab penetration status and confirmed that the failure zone dimensions are predicted within ±6% error.