The failure law of mine slope and the optimization of boundary parameter between open-pit and underground combined mining

After underground mining at the southern Antaibao open-pit mine, the slope stability in open-pit mining was studied. The research indicates that failure law of the slope rock mass for the horizontal coal seam under open-pit and underground mining exist three obvious failure zones. Underground mining causes the above three zones to exist different deformation characteristics, and the boundary parameter of open-pit and underground mining is the key factor to determine the three zones stability. Through optimized analyzing the boundary parameter, in order to guarantee the slope rock mass stability at the Antaibao south slope, the underground mining and open-pit mining must coordinate: the open-off-cut position of underground mining must be predetermined, namely taking Y=74160 as the southern boundary to arranging mining working surface. Open-pit mining, which considers the obvious influence of mining for the upside slope rock mass at the Antaibao south slope, proposes that open-pit mining of the south slope should use the design thought of "the combined slope", namely above +1375platform the geotechnical slope angle should reduce from 75° to 62.58°.