Research on the longwall top-coal caving mining technique in extremely inclined and soft thick coal seam

Taking the extremely inclined panel No. 1201 in Dayuan coal mine, Fengfeng group, as the engineering background,the basic problems of the longwall top-coal caving mining technique in extremely inclined and soft thick coal seam were systematically studied. The results reveal that the rational design of shield supports is the first necessity for the successful extraction of coal seams in such conditions. And the roof strata movement law needs to be taken into consideration during shield design. The support capacity is determined by the impact load of the roof strata in the up- per part of working face. Meanwhile,the shield supports used in extremely inclined coal seam require enough resist- ance capacity to bear the lateral compression,which should be determined combining the mining method and top-coal drawing processes. The results also show an obvious asymmetry of the drawing body and the boundary of top-coal in ex- tremely inclined seam. The method of drawing downward segment by segment while drawing upward in each segment was proposed,considering both drawing mechanism of top-coal and the stability of shied supports. By adopting such drawing method in longwall top-coal caving mining in extremely inclined thick coal seam,the negative effects on the supports during the drawing process can be minimized and a relatively high recovery ratio of top-coal can be obtained.To ensure the stability of set-up room,the opening floor was reinforced before the face installation.