Evaluation of safety state for dump slope in-service under severe drying-wetting cycles at high altitude

This study aimed to evaluate the safety of dump slopes in high-altitude areas subjected to severe dry-wet cycles. The in-service dump slopes No.1 and No.2 of the cement-used limestone mine in a high-altitude mining area were investigated. Based on the unsaturated-saturated seepage theory, incorporating the unsaturated soil shear strength equation and the matrix suction distribution equation, numerical calculations have been conducted to assess the evolution characteristics of the unsaturated-saturated seepage field and to evaluate the safety status of the dump slopes. The results indicate that the surface soil of the dump slopes shifted from an unsaturated state to a saturated state under dry-wet cycle conditions. Furthermore, as the dry-wet cycle times increased, the maximum vertical displacement of the No.1 and No.2 dump slopes increased. The numerical calculations of the maximum cumulative vertical displacement of the slope were consistent with the actual monitoring data. Although the factor of safety(FOS) of the slope decreased, it still met the safety and stability standards. Therefore, it concluded that the No.1 and No.2 in-service dump slopes were in a stable state under severe dry-wet cycle conditions.