Research On The Key Technology Of Safety Mining Along Valleys In Shallow Buried Thin Bedrock Coal Seam Of Huo Luowan Mine

The main coal seam of Huoluowan coal mine is shallow buried in depth with thin bedrock and the ground surface is loess hilly areas.During mining under valleys with thin bedrock,there are dangerous of water inrush and sand inrush in mining face.At present,research on mining under valleys is mainly focus on the slope stability and surface subsidence,there is less research on safety mining under valleys in shallow seam.Research on the key technology of safety mining in shallow thin bedrock seam along valleys has important theoretical significance and practical value.For the shallow seam safety mining along valleys in Huoluowan coal mine of Shendong Tianlong company,the overburden strata types and mining conditions of 22206 mining face under the Huhewusu valley are analyzed,and the height of overburden fracture zone is theoretically analyzed and calculated by Flac3Dand GMS.Results shows,the first roof weighting step is 45 m,and the roof caving presents "two zones",The roof caving height is 42.8 m,The periodic weighting step is about 16 m.the The shape of water flowing fractured zone is saddle shape in the goaf under the Huhewusu valleys,is height is 63.2m and it will develop to bottom of the ditch.The river valley will overall subsidence after coal mining,and the goaf also appears obvious damage phenomenon.Overburden strata fracture zone will guide through surface water,so the control measures must be taken to ensure safety mining.Based on the theory of mining under water,the four conditions of water inrush and sand inrush are analyzed,and the height of safe water head is determined as 3.74 m which is higher than the initial water level,so there is a big hidden safety problem in mining.By the numerical simulation of GMS,the hydrophobic decompression to reduce the risk of water inrush and sand inrush is feasible method.Finally,the safety mining plan of 22206 face under the Huhewusu valleys are proposed including the surface river diversion,backfill,phreatic water level,as well as the ecological restoration after mining.Through engineering practice,the key technology of safety mining along valleys in shallow buried and thin bedrock coal seam has been improved and achieve good results.