Experimental study on deformation and failure of a mining slope under the action of rainfall

Abstract

On 28 August 2017, a mining slope collapse in Pusa Village, Guizhou Province, China, resulted in the release of ~8600 m3 of earth and rock, leading to 35 fatalities. The deformation and failure mechanisms of the mining slope under the influence of rainfall was studied by a physical model test, using the Pusa Village collapse as an example. Data were collected through strategically placed monitoring points in a physical model, forming the basis for a quantitative analysis of slope deformation and failure patterns. The tested results revealed that sequential mining and rainfall activities induce progressively increasing stress variations, exhibiting a cyclical pattern of stress concentration, relaxation, and stabilization. Mining activities initiated the formation of tension and separation fractures within the model, which were subsequently exacerbated by rainfall. Rainwater infiltrating through these fractures and geotechnical bodies resulted in a more pronounced increase in water content in the upper part of the model than in the lower part. Displacement values within the model progressively increased with ongoing coal seam mining, primarily occurring in the mining area's roof and extending to the model's top following rainfall. The failure mode of the Pusa slope under combined mining and rainfall conditions is characterized by the following sequence: bending-pulling-subsidence-creep-dumping. The deformation and failure processes can be categorized into four stages: mining-induced disturbances, fractures extension and extension, formation of a potential collapse surface, and destabilization failure.