Numerical Simulation and Complexity Analysis of Strata Movement in Exploiting Steep Coal Seams Group

The mechanical characteristic of exploiting steep coal seams group face with longwall mining along the strike in Dongxia mine was simulated by using of FLAC3D software.Compared with in-site test,the strata movement behavior and complexity were also summarised.The results indicates that 1) the stress of surrounding rocks and the strata movement in steep coal seams group are more complex than in the steep single-layer seam,and 2) mining upper coal seam will affect not only the movement of overlying strata,but also the mining of lower coal seam,which is the unloading disturbance caused by mining upper coal seams and the loading disturbance caused by hydraulic power support and gob falling body.This result can provide a scientific support for engineering practice.