Most of the landslide rock and soil masses undergo cutting and fragmentation during movement, and the entry of the fragmented sliding mass into the river significantly affects the characteristics of the resulting impulse waves. The wave-making effect of the fragmented sliding mass still needs further exploration. Based on large-scale three-dimensional landslide impulse wave scale physical experiments, physical experiments were conducted to investigate the generation of impulse waves from landslides under varying degrees of sliding mass fragmentation, and the wave-making effect of the fragmented sliding mass was analyzed. The results indicate that as the degree of fragmentation of the sliding mass increases, the first peak, maximum wave height, and propagation velocity of the impulse wave all exhibit a decreasing trend. Specifically, as the degree of fragmentation increases, the maximum amplitude of the impulse wave decreases by 8.84% and 19.75%, respectively, and the maximum wave height of the first wave decreases by 12.49% and 21.13%, respectively. Through experimental observations, it is evident that the degree of fragmentation of the sliding mass primarily influences the characteristics of the impulse wave by controlling the velocity of the sliding mass and the interaction process between the sliding mass and the water body. Based on the sliding mass-water interaction, three mechanisms are proposed: sliding mass structure reorganization, seepage flow, and impulse wave attenuation. These new insights reveal the characteristics of landslide movement, fragmentation, and wave-making, and deepen our understanding of the formation mechanism of landslide impulse waves.
