Study on stability of open-pit mine slope and sensitivity of rock mass parameters

Abstract：Based on the engineering practice of the northwest slope of Antaibao open-pit mine,limit equilibrium theory and Slide software were utilized to study three key questions to analyze the slope stability.Four kinds of limit equilibrium methods were utilized to calculate and analyze the slope stability.The impact of rock mass parameters,such as rock cohesion,internal friction angle and bulk density,on the sensitivity of the slope stability was studied,and the laws of the slope stability were analyzed,and then corresponding reinforcement measures were proposed.Results show that in the application of the path search method to ascertain the most dangerous sliding surface,the suitable number of random searches of slide surface should not be less than 600 and that of slide blocks should not be less than 20.The calculation method chosen should simultaneously meet the conditions of force and moment balance.Through the calculation and analysis,the sliding of the slope is possible.The most dangerous sliding surface goes through No.9 coal seam at the toe of the slope,which should be reinforced as the emphasis.The changes in rock mass parameters,such as cohesion and friction angle of No.9 coal seam,bulk density of No.1 siltstone at the upper slope and No.2 shale at the lower slope,affect slope stability obviously.Measures including slope cutting at the upper slope,reinforcement with anchors and stacking load at the lower slope and other measures in the meanwhile are recommended.These measures are equivalent to reducing the bulk density of No.1 siltstone and increasing the cohesion and internal friction angle of No.9 coal seam as well as bulk density of No.2 shale,which can effectively improve the slope stability.No.9 coal seam and bulk density of No.2 shale,which can effectively improve the slope stability.