Abstract: The red clay has poor permeability from top to bottom, making it difficult for suffusion-induced soil arch phenomena to occur naturally. The repeated rise and fall of groundwater enhance the erosion at the rock-soil interface, causing the clay minerals within the red clay to disintegrate upon contact with water. This easily leads to the formation of localized blocks, promoting the development of soil arches, disrupting the soil structure, and providing conditions for suffusion due to the instability of the internal structure, ultimately leading to the collapse of the suffusion-induced soil arches.To elucidate the development process of this collapse type, this study combines typical collapse incidents in recent years at Dongdiu, Libo, Qiannan. By utilizing the Geo-Studio numerical simulation software, the study simplifies the groundwater erosion process as excavation to investigate the process of red clay suffusion-induced collapse in the shallow buried cover layers in karst regions. The results indicate that groundwater erosion directly impacts the seepage field and stress field of the cover layer, leading to localized stress concentration and changes in the seepage field. During seepage, the reduction in effective stress results in an increase in localized displacement of the cover layer under its own gravity, accelerating the instability of the soil structure, and promoting the development of suffusion, ultimately leading to collapse.

Key words: Karst Collapse, Sub-erosion, Soil Arch, Numerical Simulation