Study On Overburden Breakage Law And Mine Pressure Law Of Multi-seam Mining In Hongliulin Coal Mine

There are a large Study on Overburden Caving Law and Face Support Resistance in Shallow-buried Two-seam Mining number of shallow multi-seam coal resources in Western China.Most of the mines in the area are mainly mining coal seam groups.According to the production practice experience of Jurassic coalfield in northern Shaanxi for many years,the mining of lower coal seam group is prone to severe weighting phenomena such as high weighting intensity,rapid weighting,large dynamic load coefficient,step subsidence and roof fall.Studying the law of overburden collapse of shallow coal seam group and determining the reasonable support resistance of working face has become an urgent problem to be solved for safe and efficient green mining of coal seam group in Western China.Aiming at the occurrence characteristics of shallow coal seam group in Hongliulin Coal Mine,the development characteristics of water-conducting fracture zone,overburden movement law of roof breakage and support force in 4-2 and 5-2 coal seam group mining are studied and analyzed by means of on-site investigation and measurement,theoretical analysis and calculation,physical similarity simulation and numerical calculation analysis.The main conclusions are as follows:The development height of caving zone and water-conducting fracture zone in 4-2 and 5-2 coal seam group mining is determined by theoretical calculation and analysis and field measurement.The height of caving zone in 4-2 coal seam is 5.5 times higher than mining height,and the height of caving zone in 5-2 coal seam under 4-2 coal seam is 5.8 times higher than mining height;the development height of water-conducting fracture zone in 4-2 coal seam mining is 28.3 times higher than mining height,and 4-2 coal has been mined.The development height of water-conducting fracture zone in 5-2 coal seam below the seam is about 28.5 times of mining height.The research and analysis show that the pressure step distance of 5-2 coal seam under 4-2 coal seam decreases by nearly 10%and the pressure intensity increases by 14%compared with the single 5-2 coal seam mining period.The 4-2 and 5-2 coal seams in Hongliulln Coal Mine belong to the Mstep-masonry-masonry"structure type of coal seam group mining.Based on the field measurement and physical similarity simulation analysis,the "step-masonry-masonry" structural mechanics model of Hongliulin 4-2 and 5-2 coal seam groups is established,and the calculation formula of reasonable support resistance is obtained.Through calculation,the support working resistance of Hongliulin coal seam group under mining period pressure is 13143kN.