EFFECT OF UNDERGROUND TUNNEL COAL MINING TO STABILITY OF HIGH OPENPIT COAL MINING SLOPE

The high manmade slope is at the Antaibao coal mine，where underground tunnel mining and ground openpit mining are carried out at the same time. The distribution regularities of the composite stress and displacement field in the slope are analyzed by taking into account the effect of the tunnel mining direction with respect to the above openpit slope.Three tunnel mining excavation directions(ie,toward,parallel and opposite to the above openpit slope) are examined. The research results indicate that the underground mine is advanced to the stability of slope. However,the excavation direction has some effect to the slope stability. When mining from the opposite direction,the two types of different displacements are represented as the advance of working face. The topping failure is the main form of slope failure in the prophase of mining. The stability of slope is increased in the anaphase. When mining from the toward direction,the width of coal wedge reduces continuously. The slumping shear slide is generated possible. When mining from the parallel direction under the slope,the stretching failure is also generated possible. At the end,the some suggestions are given on the deformation mechanism of slope under the combined mining．