Research On The Top Slope Stability During Advance Transition From The First Mining District To The Next Of Zhundong Surface Coal Mine

The position and shape of slope has an important influence on the determination of open-pit boundary.The first mining area of Zhundong open-pit coal mine is facing some questions which are the long work line,the large stripping ratio and the far haul distance,which will increase the production cost and reduce profits.To solve this problem,the first mining area of open-pit mine will change the direction in advance to accomplish cross exploitation and inner dumping as early as possible.To determine the boundary of top slope in the first mining area is the precondition to change the direction of mining,so the reasonable slope engineering position and slope shape are the most important gist to determine the boundary of top slope in the first mining area.This paper clarifies the slope engineering geological conditions and analyzes the potential landslide model of top slope in the first mining area of Zhundong Open-pit Mine through field investigation and data collection,theoretical analysis,limit equilibrium theory and numerical simulation methods.By rigid body limit equilibrium software,the author design reasonable slope shape of different engineering position and analyze the relationship between slope angle and deep level.The article displays the distribution of internal stress and strain of slope rock mass,and analyzes the characteristics of slope deformation and destruction and reveals the mechanism of landslide by establishing two-dimensional model of the top slope based on FLAC3D.The results show that the slope slide model of top slope in the first mining area is circular slide,and the slope slide model is not influenced by the depth of the slope.In the northern part of the top slope,the mining and stripping engineering reduces from 350 to 206,and the slope angle reduces from 62°to 39°.In the middle part of the top slope,the mining and stripping engineering reduces from 350 to 222,and the slope angle reduces from 60°to 38°.In the southern part of the top slope,the mining and stripping engineering reduces from 350 to 222,and the slope angle reduces from 56°to 48°.Steep slope angle decreases with the decrease of the position of the mining and stripping engineering.The variation of slope angle is not obvious going on to reduce the drawdown level after reducing to 286,286 and 302 in the northern,middle and southern part of top slope.The failure mode of rock mass is tensile and shear type,and destroy of the local rock after slope excavation caused by stress concentration which is formed at slope toe is the inducing factor of landslide,so if in-pit dumping and press foot is realized,the stability of slope will be improved.