The Distribution Of Stress And Gas On The Lower Slice After Top-slicing Mining In Outburst Coal Seam

Taking Jiaozuo Mining Guhanshan mine and Zhongmacun mine as the study object,this paper researched the distribution of stress and gas in the lower slice after first slice mining in 21 seam. According to the request of "Coal and gas outburst prevention regulations", the use of roof and floor rock roadway wear layer pre-drainage and predrainaging integrated regional outburst prevention technology are effective ways to prevent outburst disasters. However, how would the first slice mining influence the protected effect of lower slice is still lack enough rigorous scientific investigations and researches. Researchers have various views about the hazard of the outburst in lower slice, especially for the hazard of prearranged pillar. More importantly, according to the request of "prevention of coal and gas outburst Regulation”, the hazard of outburst outside the scope of the coal mining activities within the range of 10 ~ 20 m must be eliminated.In order to research on the distribution of the gas and stress in lower slice after the first slice mining in thick coal seam. The main contents of this article are: investigating the stress distribution as well as the gas distribution changes in lower slice by layer mining technology and technical parameters, then quantitative analysis. Then providing parameters for the comprehensive outburst measures in lower slice, roadway layout and roadway ventilation design. This article could be divided into the following specific areas:(1) the working face and gas geological data collected and analyzed, slice mining technology parameters investigated;(2) Evaluating and analyzing the stress distribution,face relief effect, gas distribution and outburst elimination effect in layer slice after the first slice mining in thick seam;(3) By computer simulation and the theoretical analysis,it is known that a relief zone would be formed in the layer slice after upper slice mining.From the results of the simulation, we can know that the protective layer mining is an effective way to prevent coal or rock dynamic disasters, and it also plays a good effect in stress relieving on the protected seam;(4) Measuring the residual gas content, analysising indicators of cuttings gas and the amount of drill cuttings S after layer mining, the results showed that these data decreased significantly. Therefore layer mining is an effective way to prevent coal and gas outburst.