Study On Controlling Effect Of Tectonic Structures On Coal And Gas Outburst In The Pingdingshan Mining Area

Coal and gas outburst is a natural disaster greatly threatening underground coal mines,which seriously threatens the lives of miners and safe production of coal mines.Research on the correlation between coal and gas outburst and tectonic structures has always been an important part of gas geology studies,and also the important foundation for selection of prevention measures for coal and gas outburst.In the Pingdingshan Mining Area,the geological structures are complex,and coal and gas outburst hazards are serious.However,the controlling effect and law of geological structures on coal and gas outbursts are still unclear.In this study,based on the comprehensive hypothesis of coal and gas outburst,starting from the three factors determining coal and gas outburst,i.e.,geostresses,coal seam gas,and the physical and mechanical properties of coal,by using multi-disciplinary research methods,such as gas geology,rock mechanics,structural geology and statistics,integrated research means including field monitoring,laboratory testing,numerical modeling and theoretical analysis are adopted to reveal the controlling effects of tectonic structures on coal and gas outburst,on the basis of comprehensive and systematic analysis on the geostresses,deformed coal,coal seam gas distribution and its tectonic controlling effects in the mining area.Furthermore,the coal and gas outburst risks are predicted for the mining area.The research results can help to further reveal the controlling mechanism of geological structures on coal and gas outburst and guide the coal and gas outburst control and prevention in the mining area.The main results and understandings achieved in this study are as follows:(1)The tectonic evolution in the Pingdingshan mining area and its controlling effect on the gas occurrence of coal seam and structural formation are revealed.According to the scope and effect of the tectonic control,the geological structures in the mining area are clarified at three levels,namely,the mining area,coal mines and mining faces,the mining area is divided into seven tectonic zones.(2)The distribution of geostresses and the law of tectonic control for geostresses distribution in the mining area are revealed.The geostresses in the mining area are divided into the high tectonic stress zone in the east area,the tectonic stress zone in the central area and the vertical stress zone in the west.The high tectonic stress zone in the east area is mainly controlled by the thrust and nappe fold.The tectonic structures aresimple in the tectonic stress zone in the central area.The vertical stress zone in the west area is mainly controlled by the Guodishan rupture.(3)The distribution of deformed coal and the law of tectonic control for deformed coal in the mining area are revealed.The controlling effect of the fold and cross-bedding fault on deformed coal formation is studied,the tectonic cause of selective distribution of deformed coal in multiple layers and different zones are revealed.(4)The characteristics of gas occurrence in the Pingdingshan mining area are revealed from the viewpoint of tectonics.The difference in tectonic characteristics of the eastern,central and western parts of the mining area leads to the difference of overall distribution of gas occurrence in the mining area.In the east,the NWW-NW trending geological structures,especially the folds,are developed,which are the main reason for higher gas content in the east and lower gas content in the west in the mining area.(5)The main controlling effect of tectonic structures on coal and gas outbursts in the mining area is studied starting from the three factors determining coal and gas outburst,i.e.,geostresses,coal seam gas,and deformed coal and tectocnics controlling effect on them,the controlling mechanism of tectonic structures on coal and gas outburst is revealed,six types of tectonic structure-controlled coal and gas outbursts are proposed.According the major controlling factor for coal and gas outbursts,the mining area is divided into seven gas-geological units,the zonation and selective distribution of coal and gas outbursts in the mining area is explained,coal and gas outburst risks are predicted.