Abstract: With the increasing occurrence of extreme storm surges and strongly nonlinear wave events, sloping seawalls are exposed to significant risks of wave run-up and overtopping under the combined effects of high water levels and intense wave loading. As a representative strongly nonlinear long wave, solitary waves and their propagation, deformation, and breaking processes in shallow water provide an effective framework for characterizing run-up responses under extreme wave conditions. In this context, considering that smooth and block-armored slopes are two common forms of seawalls in coastal engineering, this study combines physicalmodel experiments with SPH numerical simulations based on the DualSPHysics+ platform to investigate the wave run-up characteristics under solitary wave action on these two types of sloped seawalls. A systematic comparative analysis of wave propagation, deformation, and run-up processes under different slope angles and wave heights is conducted. The results show that the numerical simulations agree highly with experimental data in terms of free surface evolution, breaking locations, and peak wave run-up, thus verifying the accuracy and applicability of the DualSPHysics+model in simulating strong nonlinear wave-structure interactions. Compared with a smooth slope, the block-type slope introduces pronounced disturbances to the incident wave propagation and the rundown process through its stepped geometry, inducing multiple local breaking events and enhancing energy dissipation during the rundown stage. As a result, the effective volume of the uprushing water is significantly reduced, leading to a decrease in the maximum run-up height by approximately 5%–25%, providing a theoretical basis for the optimal design of sloping seawalls and disaster mitigation.

Key words: Solitary waves, Wave run-up, Block-armored slope, SPH