Study On The Stability Of West Side Composite Slope In The Jilinguole No.2 Opencast Mine

Slope stability of open-pit mine is one of the key issues related to the safety production of open-pit mine.In October and November of 2010,the first mining area of Jilinguole No.2open-pit coal mine was stripped of the ditch infrastructure.A large area of landslides occurred in the middle and west sides of the mine.The two landslides seriously affected the development of the stripping and mining engineering,and even caused the shutdown of the mine.With the resumption of open-pit construction in 2020,the production scale is increasing year by year.How to design the reasonable shape and parameters of the west slope through stability analysis according to the current situation of the stope is the primary task to ensure the safe resumption of construction in the coal mine.This paper focuses on the study of the stability of the west slope in the first mining area of Jilinguole No.2 open pit mine.Through the engineering geological survey of the west slope,the potential landslide modes of the west slope,the dump and the composite slope are determined,and the vertical mining and horizontal mining schemes of the west slope are designed to mine the overlying 8 coal and determine the slope shape parameters.The two schemes are compared and optimized to design the spatial form of the dump slope;The stability of the composite slope is analyzed to determine the reasonable safe distance between the dump and the west slope.The results show that the potential landslide mode of the west slope is to cut through all layers with circular arc,and form combined sliding and circular arc sliding together with the weak roof layer of No.8 coal seam.The potential landslide mode of the outer dump slope is circular sliding of homogeneous material and combined sliding of circular arc and potential weak layer of basement.The potential failure mode of the composite slope is the combined sliding formed by cutting the waste materials and the Quaternary and tertiary floor.Due to the insufficient understanding of the internal conditions of the landslide area,a safe distance of 50m is set at the edge of the landslide area,and then the overlying resources are extracted vertically.Under the scheme of horizontal mining,with the decrease of the slope angle of the west slope,the displacement of the west slope presents a decreasing trend.The design of the west slope is that the width of the transport flat plate is 30m,the width of the security flat plate is 15m,and the tracking distance is controlled in the range of 50m?100m.Compared with vertical mining,horizontal mining has more mining capacity of 4568937.5t,stripping capacity of 23256423m~3and stripping ratio of 5.1m~3/t,which meets the requirement of economic stripping ratio of6.2m~3/t in the mine.The stability of the west slope can be improved by using the dual support of horizontal mining working slope and inner dump;Through quantitative calculation,when the safety distance between the dump and the stope is controlled at about 150m,the composite slope can meet the requirement of safety reserve coefficient.