Research On The Characteristics Of Methane Occurrence And Spontaneous Combustion Of Coal Of 8# Coal Seam In Wangjialing

China’s coal seam geological structure is complex,buried deep,more than 60%of the coal seam has the risk of spontaneous combustion.With the increase of coal mining depth,gas pressure and gas content increase greatly,gas problem is becoming more serious.The symbiotic disaster of gas and coal spontaneous combustion has become a common form of serious accidents in coal mines.There are few large faults in the mining area,which provides a natural environment for gas sealing,and the gas content in some areas is too large,so the corresponding gas control technical system should be established.Because fully mechanized top coal caving is adopted in coal seam,coal seam belongs to II spontaneous combustion tendency,which has the risk of coal spontaneous combustion.Therefore,it is very imperative to carry out the application in the prevention the disaster of gas and coal spontaneous combustion in Wangjialing.The monocline structure,fault structure and scour zone structure of the coal seam affect the gas distribution,so the gas content distribution shows a trend of increasing gradually from east to west.The relationship between coal seam gas adsorption capacity and existing gas pressure,coal temperature,coal seam buried depth and surrounding rock permeability is discussed systematically.The gas adsorption capacity of coal seam increases rapidly at first and then increases linearly with the increase of coal seam gas pressure,while the gas adsorption capacity of coal seam decreases gradually with the increase of temperature.There is a near linear relationship between gas content and burial depth in coal seam.The permeability of the coal seam and the risk of local gas accumulation are easy to be caused by the thickness of the middle and the thinness of the surrounding area.Through the influence of geological structure on gas distribution in Wangjialing,as well as the influencing factors of occurrence and migration of coal seam,the concrete measures of gas are formulated.It includes that the combination of hole distribution along the layer and high borehole should be considered for gas drainage.The experimental device of spontaneous combustion and oxidation of coal was used,and the corresponding gas product formation law of coal spontaneous combustion process and the relationship between initial formation temperature and coal temperature are obtained.The spontaneous combustion experiments under different oxygen concentrations were carried out,and it was found that the concentration of the main gas products decreased with the decrease of oxygen concentration.The prediction index system of coal spontaneous combustion is established:CO can be used as an index gas for predicting coal spontaneous combustion.The appearance of olefin gas C₂H₄ and C₃H₆ gas can be regarded as a sign that the oxidation of coal has entered the stage of accelerated oxidation.Finally,according to the principle of triangular fuzzy number analytic hierarchy process,the triangular fuzzy analytic hierarchy process model is established,the analytic hierarchy process is used to calculate and analyze,and the weight of the prediction index is obtained.The main control factors are analyzed and compared in detail,and it is concluded that the prediction of coal spontaneous combustion is particularly important in the prevention and control of the disasters in Wangjialing.Based on this,the technical measures for the prevention and control of compound disasters of gas and coal spontaneous combustion in coal seam of Wangjialing are established.Including fire monitoring system,development of mining and ventilation,leakage plugging,grouting,nitrogen injection,inhibitor and gas extraction as the core technology of the prevention and control system.The paper contains 29 figures,12 tables and 94 references.