Destabilization mechanism of the Yanxincun landslide in Tongjiang County, Sichuan Province under the influence of pond water seepage

Landslides caused by human engineering activities occur frequently, yet studies specifically addressing those triggered by pond water seepage remain limited. In this paper, the Yanxincun landslide in Tongjiang County, Bazhong City, Sichuan Province, is taken as a case study. Based on unsaturated seepage theory, the slope stability is analyzed under three working conditions: natural conditions, steady-state seepage, and steady-state seepage combined with transient rainfall. By integrating quantitative and qualitative evaluations, the destabilization mechanism of this type of pond seepage-induced landslide is revealed. The results show that under steady-state seepage condition, the internal geotechnical body exhibits strong anisotropy, resulting in the formation of preferential flow channels within the body. This process gradually deteriorates the physical and mechanical properties of the geotechnical body, particularly when coupled with the influence of transient rainfall. Rainfall serves to augment the downward sliding force of the landslide. The combination of steady-state seepage and transient rainfall is identified as the direct cause of the landslide along the Xincun Village. Moreover, slope stability is shown to be a dynamic process that changes over time. This study provides a valuable reference for understanding the destabilization mechanisms of similar landslide types, particularly in the context of preventing landslide-related geohazards in mountainous regions with prevalent agricultural and irrigation activities.