Study on mine strata pressure law of fully-mechanized coal mining face under coal pillars and goaf in contiguous seams

In order to study the coal pllar at the top section of the contiguous seams and the goaf affected to the mining operation of the fully-mechanized coal mini ng face in the underneath seam, a FLAC3D numerical simulation software and engineering practices combined method was applied to study the mining stress distributio n law of No.2-2. 601 fully mechanized coal mining face of Sanjiaobe Coal Mine with the coal pillars left in the above mined seam and under the goaf of the above seam. The results showed that under the coal pillars and goaf in the above seam, the mine strata pressure behavior of the fully mechanized coal mining face would have differ ent laws. Under the coal pillars in the above seam, the max working resistance of the powered support was higher than the powered support load under the goaf in the above seam. During the periodical roof weighting, the circulated end resistance of the powered support under the coal pillars in the above seam was 332.1 k N higher th an under the goaf in the above seam, the average roof weighting step distance was increased by 1.7 m and the dynamic loading coefficient was reduced by 8%.The loa d under the two sidewalls of the coal pillars in the above seam was higher than the load under the central part of the coal pillars. When the peak value occurred in the C entral line of the coal pillar in the above seam, the influence area would be right under the coal pillar in the above seam and would be 10 m under each of two sidewalls.