1.School of Energy and Mining Engineering,China University of Mining and Technology(Beijing),Beijing ,China;2.Shanxi Coal Import and Export Group Hequjiuxian Open Cut Coal Industry Co.,Ltd.,Hequ ，China;3.Inner Mongolia Lijiata Coal Mine,Ordos ，China

In order to study the stability of the dump slope in the open-pit coal mine of Hequ Jiuxian under rainfall conditions to ensure the safety of buildings such as the coal preparation plant on the west side of the slope body, the FLAC 3D software was used to determine the potential slip surface by the strength reduction method, and the fitting model of the potential slip surface is established by the FISH language. The ultimate stability calculation software geo-slope was used to analyze the overall stability of the current slope and the final abandoned slope under natural conditions and heavy rain conditions. Secondly, the simulation calculation is carried out for each working condition of the slope body using different presser foot parameters, and the safety factor under different conditions and the position of the sliding body shear outlet were obtained. The results show that under natural conditions, the current slope and the final abandoned slope can reach a stable or basically stable state. However, under heavy rain conditions, the base of the slope body has a weak layer, and the mechanical parameters of the slope are seriously weakened. The safety factor drops sharply, the range of the sliding surface and the sliding body expands, and the sliding body is cut from the foot of the slope to be cut out from the weak layer of the base. The safety factor of each typical section is reduced by 20%～30% compared with the natural working condition. The probability of stability is extremely large. According to the specific conditions of the dumping site, the slope foot process is used to improve the stability of the dumping field and optimize the process parameters of the height and width of the presser foot. Adopting a presser foot with a width of 40 m and a height of 20 m to ensure the stability of the slope.

国家重点研发计划资助项目（2018YFC1504802）；国家自然科学基金资助项目（51474220）；越崎杰出学者资助项目(800015Z1179)