Surface Movement Laws in Mining Steep Coal Seam Group of Thin Soil Layers

We uses the Universal Distinct Element Code (UDEC) to analyze the laws of mining subsidence in steep coal stratum in Qingshan Coal Mine, as well as to research of surface deformation caused by coal seam mining and the main coal seam under the condition of repeated mining strata movement law of roof and floor, and analyzed surface discontinuous deformation and sudden failure generating mechanism under the condition of steep coal seam repeated mining. Based on mastering the surface movement law at the same level of coal mining, through the surface deformation parameter evaluation, we propose that it is given priority to mine hard coal seam from -300 to 0 m range in model as building land, and appropriately increase stage coal pillar; from 850 to 1200 m range as building land is given priority to mine large groove seam.