Analysis on deformation development of open-pit slope under the influence of underground mining

With continuous excavation, more and more open-pit mines are gradually transformed to underground mining, and the northwest slope of the Antaibao open-pit mine in Shanxi province is under the influence of underground mining now. Based on the slope engineering, the engineering background and present deformation characteristics of the slope are introduced. The deformation response characteristics of the steep slope under the influence of combined mining were researched by the numerical simulation software FLAC(3D), and it was demonstrated that the steep slope formed by open-pit mining had new characteristics and tensile cracks occurred after underground mining of No. 4 coal and No. 9 coal seams. The displacement vector clearly changed, with maximum ground subsidence about 3.12 m and maximum displacement toward free face about 0.48 m. According to the deformation curves of monitoring points located on the slope, the deformation had a periodic change with the seasons, and the rainy season was the most intense period of deformation development, when the tensile cracks on the top of the slope became a seepage channel of rainwater. By studying the deformation process of open-pit slope under the influence of underground mining, the deformation development characteristics were got, and it could provide guidance for the reinforcement measures of landslides and ground subsidence.