Simulation Study On The Moving Rule Of Roof Of Mining Coal In Two Gently Inclined Thin Seams

In China, the reserves of thin coal seam take 20 percent of total coal reserves, With the exhausted of recoverable reserves, the thin seam mining has become the inevitable question during the coal mining in many mine shafts.The Muchengjian colliery of Haohua group Beijing has entered the mining phase exploitation phase. Which +250m level, No.2 and 3 spout, West No.1 winning district was gently inclined thin seam, a proper spacing between two spouts. For the actual situation of gently inclined coal seam, base on the feature of coal seam roof, floor, and the rock in interlayer, in order to the reasonable development and utilization of thin coal seam and increase recovery, reverse the two slots with the proposed mining.For the breakage for coal floor of gently inclined thin seam, base on the full research, take the methods of theoretical analysis, similar material simulation experiment and numerical simulation combined, have a system research on the law of rock pressure, the deformation and damage mechanisms of roof and control measures under this mining scheme and synchronous production method. Dynamic analysis the deformation and failure process of the roof, floor and wall rock in interlayer, identified the first roof weighting pace and the periodic caving of immediate roof in the working face. Explicit caving angle of immediate roof failing, determinate the face advanced distance and the roof of gate settlement distance by displacement sensor. Make sure the maximum distance of settlement before the limit of immediate roof initial caving. Analysis the key factors which influence the safe mining o working face and safety support of anchor and list. Search the monitoring method and techniques of roof, floor in working face. Analysis the deformation rule of drift, failure mechanism, stress distribution and the reinforcement effect of supporting pillar under the conditions of different support program.The results show that: After the roof pressure for many times, the roof of No.2 spout falling in a large scale in huge mined-area, made the upper part of the rock of No.2 and 3 spout integral subsidence. Avoid the damage of the coal seam of No. 3 spout and roof, Create favorable conditions of mining coal of No. 3 spout. With the advanced of No. 3 spout's working face, the roof of No. 2 spout falling in a large scale, compactness the coal seam of No.3 spout and above seam. improve the integrity of roof strata, It was benefit on coal mining of No.3spout, but because of the roof falling in a large scale, will produce external powerful impact, exerted a lot of pressure on working face and roadway, so must be strengthening support , to ensure safe produce.When take the support of 10 meters'chain pillar, the upper parts of the coal pillar suffer an uneven distribution rock stress. Appear the phenomenon of stress concentration, the degree of stress concentration would be lower after mining, the roof go downward. The roof couldn't fall normally to formation the roof fall. May appeared the subsidence of ground surface. When ignored the support of coal pillar, because of the bulk factor. The rock falling down will full of the mined-out region .Which conducive to the safety of the ground construction. The numerical simulation and experimental results revealed the failure law of the roof and control measures from safety and economy. And have an important guiding significance on theoretical study and production practice for related issues.