E24 Profile Slope Stability Evaluation In Haizhou Opencast Coal Mine Of Fuxin City

The E24 profile slope analyzed in this study belongs to a series of excavated slopes located at the North Slope of Haizhou Opencast Coal Mine; its stratigraphy presents two noticeable coal seams, called 8# and 9# weak layers, considered as potential failure surfaces; it seems to be divided into downslope part and upslope part. In consideration of the actual profile and in the expectation of earthworks and development projects envisaged within this abandoned mine, analyzing stability with each weak layer under given conditions and quantifying instability risk of this slope using both the conventional limit equilibrium methods and the finite element methods, have constituted the main objectives.First from each weak layer, particular profiles and corresponding critical slip surfaces are defined and specified; then rigorous limit equilibrium methods implemented in Slope/W computer program are used to obtaining more or less significant critical safety factors; at last stability computations of these particular profiles are performed using both Sigma/W analysis based on finite element method to establish total vertical in-situ stresses, and Slope/W analysis to determine finite element stability factors before to compute factors of safety for comparing with these stability factors. All the critical factors of safety computed with 9# weak layer without groundwater conditions using adopted limit equilibrium methods are lower than with groundwater; however they are higher than the values of the both stability factors and safety factors determined by using the finite element stress-based method. The stability computations of E24 slope indicate that 9# weak layer is the least favorable slip surface without endangering the slope stability in short and long-term; however the instability risk exists during earthworks on its surface. The values of stability factors and safety factors obtained by finite element stress analysis method are more realistic and accurate than those from traditional limit equilibrium methods.