Study On The Movement Of Overlying Rock And The Law Of Mine Pressure Appearance In The Mining Of Thin Coal Seam Under The Goaf Of Liangshuijing Mine

The lower coal seam of the shallow coal seam group is under the goaf of the upper coal seam,and its roof structure is different from that of the single coal seam mining.When mining the lower coal seam,it will cause the second disturbance to the overburden,which will have a great influence on the mine pressure.Based on the engineering background of the 431301 fully mechanized face in Liangshuijing coal mine,this paper studies the overburden structure,the movement law of overburden and the law of mine pressure appearance by means of theoretical analysis,numerical simulation,indoor experiment and field measurement.The main research results are as follows:(1)Based on the geological conditions of Liangshuijing coal mine and the laboratory test data of field sampling,the key layer of 4-3 coal roof is identified,and the siltstone of the interval layer is determined as the key layer,and the overburden structure is a single shallow key layer structure.(2)The stress distribution law of 4-3 coal before mining is studied by numerical simulation.It is found that there are stress reduction area and stress recovery area in the roof of the side of the opening.On this basis,the theoretical analysis shows that the initial step distance is 45 m,and the periodic step distance is 22 m.The analysis shows that the initial roof is an asymmetric three hinged arch structure,and the periodic top plate is a masonry beam masonry beam structure.(3)The numerical simulation method is used to analyze the law of mine pressure appearance of different comprehensive mining face's advancing speed.The results show that after the increasing of advancing speed,the breaking length of direct roof and basic roof increases,the activation degree of the disturbed key layer of 4-2 coal is high,the movement of overburden is more intense,and the load on the bottom plate of goaf is greater,and the peak value of the leading bearing stress of the stope increases,and the distance from the coal wall decreases Small.(4)Based on the analysis of the pressure structure,the working resistance of the first pressure support is calculated;according to the difference of the breaking positions of the key layers of 4-2 coal and 4-3 coal,the non synchronous rotary sinking structure of the key layer and the synchronous rotary sinking structure of the key layer are proposed,and the reasonable working resistance of the stope support is calculated by theoretical analysis.The results show that the ZY9000 / 09 / 16 d type support selected on site works The resistance meets the production requirements.At the same time,numerical simulation is used to analyze the influence of increasing the working resistance of support on the control effect of stope.The on-site ground pressure observation shows that the ground pressure of the thin coal seam under the shallow coal seam group is more intense than that of the shallow single coal seam mining,the periodic pressure strength is greater than the initial pressure,and the resistance of the support in the middle of the comprehensive mining face is greater.Therefore,the management of the support in the middle should be strengthened to ensure the on-site safety production.There are 92 figures,19 tables and 87 references in this paper.