Analysis of influencing factors on concrete fracture characteristics subjected to pulsed water jet and prediction model of fragmentation efficiency

Abstract Pulsed water jet (PWJ) technology offers a promising approach for concrete demolition, leveraging high‐frequency dynamic loading and a reduced water‐cushion effect. However, the dynamic damage mechanisms and stress evolution in concrete under PWJ impact, along with the influence of key parameters on fragmentation efficiency, remain inadequately understood. This study adopts an SPH‐FEM coupled algorithm to simulate and analyze the dynamic damage and stress evolution in concrete subjected to PWJ, with continuous water jet (CWJ) serving as a comparative benchmark. Using orthogonal experimental design and multivariate nonlinear regression implemented in Python, sensitivity analysis of key parameters—including pulse length, pulse spacing, jet velocity, jet diameter, and concrete strength—was performed, and predictive models for fragmentation efficiency were developed. The results show that PWJ effectively utilizes water‐hammer pressure to enhance crack propagation, with damage evolution exhibiting directional anisotropy and progressing through three distinct phases: non‐damage, damage accumulation, and complete failure. The horizontal damage range is localized within 4–5 times the jet diameter, and damage duration follows a power function horizontally and an S‐shaped curve vertically. Jet velocity exerts the most significant influence on broken pit depth and area, while jet diameter is the dominant factor for width. Concrete strength inversely affects breakage efficiency, reducing pit area exponentially. An optimal pulse spacing of 4 mm improves broken pit depth and area. Multivariate regression models for broken pit depth, width, and area achieve high accuracy ( R 2 : 0.912–0.944, mean deviation <1.1%). Optimization recommends high velocity, large diameter, short pulse length, and moderate pulse spacing. These findings could provide theoretical and practical guidance for enhancing PWJ applications in concrete fragmentation.