Underwater blast response and pile failure analysis of submerged reinforced concrete piles and pile group foundations

This paper presents three-dimensional (3D) nonlinear finite element analyses of pile foundations in saturated sand deposits subjected to submerged explosions. In this contribution, the explosive response and failure analysis of reinforced concrete piled foundations and blast induced wave propagation are investigated. The arbitrary Lagrangian-Eulerian (ALE) analysis tool available in the finite element software LS-DYNA is employed to simulate blast loadings. Parametric sensitivity studies are conducted for pile reinforcement arrangements, explosive charge mass, and the effect of pile head constraint conditions. Also, explosive stress wave propagation in saturated media is investigated. For this purpose, extensive numerical modellings are performed under different explosive charge shape and weights. By adopting suitable material models, the strain-rate-dependent behavior of saturated soil domain, steel reinforcements, concrete piles, and cap piles are simulated. Pile lateral displacements, explosion wave velocity, stress distributions, and pile foundation damages are illustrated in order to study the dynamic response of submerged pile foundations. It has been observed that, the reinforcement arrangement has significant effects on the behavior of the piles subjected to submerged explosions. It was also observed from results that the pile spacing in a pile group affects the bearing capacity of pile groups under explosive conditions. The findings of this research provide valuable information regarding the effects of underwater explosions on submerged piled foundations, guide engineering designers and are considerable for design codes.