Studies On Strata Behavior Arround Fully Mechanized Multi-Slicing Top-Caving Faces Mining Steeply Dipping Thick Coal Seam

When the steeply dipping seam employs longwall mining along the strike direction is employed, the waste rocks fill the gob non-homogeneously along the dip direction, the deformation and caving of surrounding rocks exhibit obvious asymmetry and spatio-temporal characteristics with particular and complex strata behavior. The coal seam of No.37220 section in Dongxia coal mine is steep(55°~74°), extra thick(19.6m) and complicated in structure, we have finally decided to adopt the sub-inclination longwall-along-the-strike fully mechanized top-caving mining method. Thus, it is of great practical significance to get hold of the law of overburden movement and strata behavior, improving resource recovery, increasing the economic benefit and realizing safety production operation.This paper by means of theoretical analysis, physics simulation, numerical simulation and field observation, the characteristics of strata behavior are studied in the No.37220 section. The result shows that:(1) The weighting interval of Sub-inclination 37220-1 is larger than Sub-inclination 37220-2’s, while the support pressure and strata behavior Sub-inclination 37220-2’s are larger than Sub-inclination 37220-1’s.(2) The pressure of powered supports is of subarea characteristic, the Sub-inclination 37220-1 support pressure present the lower part is the maximum, the middle part is the second, and the upper part is the minimum. However, the Sub-inclination 37220-2 present the middle part is the maximum, the upper part is the second, and the lower part is the minimum. In steeply dipping fully mechanized top-caving face, the front legs pressure is higher than that of the rear legs’ and the two-leg shied is superior to four-leg choke-shield.(3) The abutment pressure of Sub-inclination 37220-1 present the lower part is the maximum, the middle part is the second, and the upper part is the minimum. However, the Sub-inclination 37220-2’s abutment pressure present the middle part is the maximum, the upper part is the second, and the lower part is the minimum. The abutment pressure, influence area and average stress concentration coefficient of Sub-inclination 37220-1 are all larger than Sub-inclination 37220-2’s.(4) As the layout of working face adopts “horizontal line–arc segment–inclined line”, the stress distribution and plastic zone distribution of coal and rock is asymmetry in arc segment and inclined line.(5) The steeply dipping extra thick coal seam employs sub-inclination mining method, the waste of upper sub-inclination’s gof could fill the lower sub-inclination void, which benefit to roof control of lower sub-inclination.Field practice shows that theoretical and experimental analys are according with field practical, and achieved better technical and economic benefits. Our study provides a reference for safety and efficient mining for steeply dipping fully mechanized top-caving face under the similar conditions.