Abstract
To reduce the risk of roof falling and rib spalling during equipment retracement in thin coal seam faces with soft roofs, the 25070 working face of Xuehu Coal Mine was taken as the research object, and theoretical analysis, numerical simulation, and field practice methods were used. Under different space relationships between retracement channels and main roof fracture, the load of hydraulic supports was quantitatively analyzed. The relationship between the working resistance of the hydraulic support and the sinking rotation angle of the immediate roof was analyzed, and a reasonable time for the arrangement of the retracement channel was determined. The sublevel excavation technology and the combined support technology of roof anchor cables and coal rib anchors were proposed. The field application shows that the falling height and rate of movable prop of the hydraulic supports, working resistance of the hydraulic supports, and the roof subsidence all meet the requirements of safety production during the terminal mining period, and the surrounding rock control effect of retracement channel was determined to be good. The safe and efficient mining of the coal mine is ensured, and the research results can provide guidance for similar working faces.
Highlights
To reduce the risk of roof falling and rib spalling during equipment retracement in thin coal seam faces with soft roofs, the 25070 working face of Xuehu Coal Mine was taken as the research object, and theoretical analysis, numerical simulation, and field practice methods were used
Introduction e retracement of working face equipment is an important link of coal mine mining [1]. e retracement channel connected with the working face needs to be set in the stopping line for the retracement of working face equipment, which is different from normal mining. e characteristics of large sections, equipment, complex technology, and close proximity to the rear gob determine that only by reasonably setting and supporting the retracement channel, the working face equipment can be safely and quickly retraced [2]
Taking the 25070 working face of a typical soft roof thin coal seam in the Xuehu Coal Mine as the research site, the Xuehu Coal Mine is located in northern Yongcheng City, Henan Province, China, as shown in Figure 1. e No 2 coal seam of the Shanxi Group is mainly mined, and it has the risk of coal and gas outburst. e 25070 working face is located in the east of 25 mining district. e ground elevation is +37.0 m, and the working face elevation is −793 m ∼ −711 m
Summary
Taking the 25070 working face of a typical soft roof thin coal seam in the Xuehu Coal Mine as the research site, the Xuehu Coal Mine is located in northern Yongcheng City, Henan Province, China, as shown in Figure 1. e No 2 coal seam of the Shanxi Group is mainly mined, and it has the risk of coal and gas outburst. e 25070 working face is located in the east of 25 mining district. e ground elevation is +37.0 m, and the working face elevation is −793 m ∼ −711 m. E main roof breaks and deforms when the 25070 working face is weighting. E immediate roof directly is extruded by the main roof and the hydraulic support. As the depth of the hole increases, the deformation of the hole wall decreases until the main roof is not significantly damaged. When the working face is weighting, the immediate roof is broken compared with nonweighting and the control of the roof of the working face is more difficult
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