Research On Gas And Coal And Rock Dynamic Disaster At The Condition Of High Geostress In Deep Coal Seam In Zhu Jixi Mine

In the process of coal mine production,with the increase of the mining intensity and the mining depth,superior occurrence of coal seam in our country are greatly reduced,the production environment becomes more and more complex,coal mine safety is under a greater threat because of the coal-rock and gas dynamic disasters caused by high geostress and complicated gas occurrence conditions.The dynamic disaster of coal and rock has become one of the worst coal mine disaster due to its devastating characteristics of sudden and violent advent,and causing large casualties and huge economic losses,but the most serious disaster in coal mine has not been fundamentally controlled up to now.In this paper,we take the typical working faces of 11-2 coal seam with dynamic disasters in Zhu Jixi coal mine of Wanbei coal-electricity group company as the research object.Through the integrated research methods such as laboratory testing,theoretical analysis,numerical simulation,and field industrial test,and the test of the mechanics characteristics parameters of coal-rock and gas,the disaster-causing mechanism analysis and classification attributes identification of coal-rock and gas dynamic disasters of the mining face,coal and gas dynamic dangerous areas division,to establish the prevention and control measures for coal-rock and gas dynamic disasters during the mining of fully mechanized face,provide the basis and support for its prevention,and provide important reference and theoretical guidance for other mines with similar conditions to carry out the prevention and control work of the coal-rock and gas dynamic disasters.The main research results and related conclusions of this paper are as follows:(1)The gas pressure of the 11-2 coal seam is relatively small,and it is not obvious along the dip direction.The local gas pressure is relatively big,gas content is relatively small,gas desorption characteristic is not good,and the effect of gas in coal and rock dynamic disasters is weak.The coal seam is in the transition complex zones with N2-CH4 and CH4.The occurrence regularity of gas content and gas pressure is not obvious.The hanging depth from the surface to 11-2 coal seam is around 1000 m,so the coal seam is in high ground stress and super high stress dangerous area.According to the laboratory coal and rock impact tendency test results,the hard coal sample of the coal seam has weak impact tendency,and the sandstone roof strata has a strong impact tendency.(2)This thesis points out that when mining the coal seam with gas in deep mine,coal and gas outburst is relevant with rock burst.The occurrence of rock burst can cause the gas emission,and thus lead to the coal and gas outburst accident.Coal and gas outburst is the boost of rock burst.Therefore,when monitoring the coal and rock dynamic disasters in the mine,coal and gas outburst should be monitored together with rock burst.They are early warning signals of each other.(3)According to the energy essence of the occurrence of coal and gas outburst and rock burst,the thesis analyzed the energy source,and established the energy equation of coal and rock dynamic disaster,which is E_e+E_f+E_d=E_e+E_r,namely the elastic strain energy accumulated in coal and rock mass,and the gas expansion energy could lead to the coal and rock damaged and thrown,different degrees of participation of gas determined the forms of coal-rock and gas dynamic disasters.This thesis also analysed the energy transfer process of instability failure of coal-rock from the view point of energy,and put forward the judgment criterion of dynamic disasters.(4)Adopting numerical simulation to study the changing rules of coal seam stress,gas pressure and the plastic strain areas of the coal seam in Zhu Jixi mine in the process of mining under the different geological conditions,analyze the risk of the occurrence of gas outburst,and demonstrate that the risk of outburst is directly proportional to the buried depth of coal seam and the size of the gas pressure,and inversely proportional to the thickness of the coal seam.Based on the engineering geological conditions of 11-2 coal seam,this thesis points out that in the synthetic actions of this three kinds of influence factors,it is easier to form the high stress areas and appear coal and gas outburst where is closer to the working face,and the prevention and early warning work should be carried out.(5)The thesis divided the high ground stress dynamic dangerous areas,and four areas as coal and gas outburst dangerous areas within the scope of the working face,and adopted the comprehensive index method and rock burst dangerous factors coupling method to predict and classify the ground stress dynamic dangerous areas of the working face and determine the face square areas,both sides of fault and fold zone,and the stop mining areas are respectively strong dangerous areas and the medium dangerous areas,and the other normal mining areas are the weak dangerous areas.The successional coal and gas risk drilling in working face index regional verifying should be implemented for the key preventive areas,and the coal and gas risk drilling in working face index regional verifying can be implemented at 30~50 m intervals in the general preventive areas.(6)Based on the ground stress dynamic risk comprehensive index method and multi-factors superposition method of comprehensive regional prediction,in combination with gas geology method of coal and gas outburst regional prediction,the thesis adopted the compound area measures such as regional gas pre-drainage to achieve the standard,unloading,water injection measures to reduce the outburst tendency of coal seam,and regional measures such as strengthening support and optimizing the mining and extraction technology and speed,the effect inspection of regional outburst prevention measures,working face advance abutment pressure and support working resistance on-line monitoring,dynamic risk prediction of drilling cuttings index,shallow holes dynamic pressure water injection and drilling pressure relief measures as supplementary,which is "first the area,then the local" comprehensive prevention and control system,so as to achieve the purpose of preventing and controlling coal-rock and gas dynamic disasters all-round and three-dimensionally.(7)Under the premise of grasping the characteristics of gas occurrence in working face and disaster strata,optimizing gas control measures project in time,so as to achieve the goal of integration of safety,technology and economy.