Experimental Study on Wave-Induced Pore Pressure Response and Instability of Layered Submarine Clayey Slope

Wave-induced submarine slope instability and its subsequent submarine landslide pose a huge threat to the coastal communities and offshore infrastructure. This study conducted a wave flume experiment to understand the effect of low-permeability layer on the excess pore water pressure response and the instability of the layered submarine clayey slope under wave actions. The experiment captured the whole process of soil progressive liquefaction and instability of submarine clayey slope. When the wave propagates from the toe to the crest of the slope, the wave shoaling results in the soil at the slope crest above the low-permeability layer liquefy and then slide down due to the wave oscillation and scouring. The low-permeability soil layer leads to a delay in the accumulation of excess pore water pressure. However, once the excess pore water pressure is accumulated, this layer restrains the dissipation of excess pore water pressure resulting in significant liquefaction potential of the soils below this layer. Due to the capping effect of the low-permeability soil layer, there was no significant sliding of the soil mass below it. Our findings might provide an implication and guiding significance for offshore site selection and the coastal engineering safety.