Failure analysis of concrete by submerged water jet impact

Abstract To address the challenge of demolishing concrete structures in submerged environments, this paper conducts experiments on submerged water jet impact crushing of concrete. Using acoustic emission equipment and computed tomography scanning technology, combined with a submerged jet impact concrete model created through numerical simulation software, the study investigates the external macroscopic crushing characteristics, crack propagation patterns, internal damage distribution, and fracture mechanism of submerged jet‐induced concrete failure. The experimental results indicate that the submerged water jet crushing process can be divided into a centralized crushing zone and a derivative crushing zone, with the central crushing area forming an approximately circular pit‐like structure. Through the established submerged water jet impact concrete model, the internal damage mechanism reveals that the concrete is primarily subjected to shear stress, leading to ring‐shaped cracks and local spalling, ultimately forming a “V”‐shaped crater. By analyzing peak pressure and damage factor parameters, the optimized water jet parameters are identified as a jet velocity of v = 650 m/s, angle θ = 75°, diameter r = 2.5 mm, and target distance d = 7 mm. This research enhances both the theoretical understanding and practical application of submerged jet concrete crushing technology, supporting the maintenance and repair management of underwater concrete structures.