The Influence of Shell-Sand Mixing on the Dynamic Response of the Seabed Foundation in Front of a Slope Breakwater

Shell-sand mixing, as a novel technique for coastal protection and seabed improvement, holds broad application prospects. However, the underlying mechanism of its influence on the wave-induced dynamic response of the seabed beneath slope breakwaters remains unclear. In this study, physical model experiments were conducted in a wave flume to analyze the effects of shell-sand mixing on the amplitude of pore water pressure in front of the breakwater and the vertical attenuation coefficient of the seabed. The results indicate that the amplitude of pore water pressure decreased by up to 46.5% after the application of shell-sand mixing. As the mixing ratio of shell-sand increased, the vertical attenuation coefficient of pore pressure initially rose and then stabilized. When the shell-sand mixing ratio reached 15%, the average vertical attenuation coefficient of pore pressure had already stabilized. Furthermore, this paper established an empirical formula for the pore pressure response of shell-sand mixed seabed in front of slope breakwaters, applicable to sandy seabeds. The correlation coefficient R2 between the predicted values from the formula and the measured data reached 0.881. This research provides a scientific basis for the engineering application and improvement evaluation of shell-sand mixing. The study also assessed the application of shell-sand mixing technology along the West African coast, with results indicating that the Western Sahara region is the most suitable area for implementing this technique.