Abstract Addressing the surface erosion challenges faced by river‐ and sea‐crossing bridge piers under severe localized hydraulic impact, the coupled numerical representation of high‐speed fluid impact, large deformation of the protective layer, and brittle fragmentation of the substrate remains challenging. To this end, this paper proposes a unified fluid–structure interaction numerical framework tailored for the “high‐pressure water jet‐polyurea coating–concrete” heterogeneous system. Centered on the Generalized Interpolation Material Point Method (GIMP‐MPM), the framework integrates the Weakly Compressible Newtonian Fluid (WCNF) model, the Holmquist–Johnson–Cook (HJC) damage constitutive model for concrete, and the Yeoh hyperelastic constitutive model for polyurea, overcoming the bottlenecks of traditional grid methods in simulating large deformations of multiphase media and interface evolution. Validated by high‐pressure water jet erosion tests, the established model can characterize the erosion pit evolution of both plain concrete slabs and polyurea‐coated concrete slabs within a reasonable error range. Based on this model and the first‐order wave impedance mismatch theory, the dynamic protection mechanism of the polyurea layer is jointly revealed: the polyurea layer achieves a “soft landing” buffering effect due to its high impedance matching characteristics with the water medium. Furthermore, under the continuous impact of a water jet at 200 m/s for 5 s, the wave reflection mechanism at the interface reduces the local maximum stabilized equivalent stress within the substrate from 29.8 to 22.7 MPa, forcing the stress concentration zone to significantly contract from deep to shallow layers. Macroscopically, an 11 mm thick polyurea coating reduces the slab erosion depth by approximately 85% at 5 s and suppresses the depth growth rate to within 16% of that of the plain concrete slab during the stable erosion stage. This study demonstrates that the proposed MPM‐based WCNF–HJC–Yeoh framework provides a quantifiable theoretical basis and predictive tool for the erosion‐resistant resilience design of hydraulic structures.
Huang et al. (Sun,) studied this question.