Multi-scale analysis of seepage and erosion on collapse accumulation slope

This study focused on the slope surface of debris deposits during the Luwei Sea landslide. Through seepage erosion tests, nuclear magnetic resonance and the coupling of computational fluid dynamics with the discrete element method, the seepage erosion of four representative areas on the slope surface was systematically studied at the macroscopic, mesoscopic and microscopic levels. The results showed that the particle size distribution has a significant impact on the seepage erosion characteristics. When the ratio of soil to rock was higher, soil–rock mixture showed stronger resistance to infiltration and soil protection during seepage erosion. The applied osmotic pressure also affected seepage erosion. However, when the osmotic pressure exceeded a certain critical value, pore blockage became the main mechanism of seepage erosion. Furthermore, a vegetation-based soil stabilization method involving geotechnical reconstruction and material soil stabilization in unvegetated areas was proposed, thereby promoting vegetation growth and enhancing slope stability. Our findings provided effective measures and a strategic theoretical basis for the rehabilitation of mudslide accumulation sites.