Study Of Residual Coal Repeated Mining Face Pressure Feature In Thick Coal Seam Small Kiln Destruction

Residual coal repeated mining face of thick coal seam small kiln destruction because of its special rock conditions to show pressure characteristics certainly exist particularity.This article study the impact of thick coal seam small kiln residual damage zone "empty area-coal pillar" the stability of the law of repeated mining face pressure by residual damage zone small kiln "empty area-coal pillar" stability mechanical analysis and using numerical simulation analysis tools and the method of integrating the pressure and so on. Conclusions are as follows:1) Residual coal repeated mining can be grouped into three basic types:â‘ fully adopt the empty area type repeated mining;â‘¡Vertical leap coal columnar type repeated mining;â‘¢Across coal columnar type repeated mining. At this stage the repeated mining face are complex by more than two or three of the above three types. The focus of this article is the residual coal repeated mining face of thick seams kiln damage zone that cross the coal pillar type repeated mining.2)The stability of residual "empty area-coal pillar" mechanical analysis shows:The capitals plate stress distribution of the thick seams kiln damage zone the residual coal has been changed. The residual coal repeated mining face is located in High stress region of the top of the coal pillar stress concentration passed to the backplane;thick coal seam small kiln damaged areas of residual coal repeated mining Roof four kinds of mechanical model:â‘ entities coal pillar mechanics model;â‘¡The completely empty area mechanics model;â‘¢The roof Collapse not fully empty area mechanics model;â‘£The roof fall full of empty area mechanics model.3) Combined numerical simulation analysis knowed:â‘ When minig face through wider residues goaf, its roof vertical stress performance out the law of "weak-strong-weak-strong-weak", and the stress peak of out of goaf ago larger than entered in goaf; The difference of residues goaf backplane rock sexual is unlikely to repeated mining face roof pressure distribution law, but when residues goaf backplane for rock, repeated mining face roof appeared vertical stress smaller.â‘¡residues coal column on repeated mining face pressure appeared of effect:the pressure of repeated mining face mine under narrow coal column is smaller and no law; when coal column is wider,the pressure of mining face performance for law of middle large and ends small, peak appears in partial produce coal column of location; the pressure of face under widest coal column performance out law of "weak-strong-weak-strong-weak", mining face entered coal column roof pressure reduces, when it across2m,mining face pressure is minimum, when entered coal column6-7m, the roof pressure reached peak, Produce coal with precolumn4m pressure peak once more and greater than when we entered to coal pillar peak.4) when Studied of measured results of2107repeated mining face pressure,it can be kowned:when mining face on one or both sides enter the pillar5-10m area at the same time, measured data of working resistance of hydraulic support are increased. When it on one or both sides at the same time produce coal pillar4-6m range, mining face pressure again increased, but higher than into coal pillar5-10m area resistance to be. For32#hydraulic support, the peak pressure of leaving coal column is1.2times to enter into the pillar. 5) The regularity effect of residue "empty area-pillar" to mining working face pressure mainly as follows:â‘ setting the residual coal pillar width is L, when L<8m, the pressure of repeated mining face is no obvious rule; when8m<L<15m, the pressure law of repeated mining face appear as "weak-strong-weak"; when15m<L<25m, the pressure law of repeated mining face appear as "weak-strong-strong-weak"; when L>25m, the pressure law of repeated mining face appear as "weak-strong-weak-strong-weak";â‘¡The pressure law of repeated mining face under goaf multiple displays "strong-weak-strong".