Research On Spontaneous Combustion Of Coal Seam And Slope Stability In Bainaimiao Coal Mine

Coal is an important foundation and mainstay of my country's modern energy system and the basic guarantee for achieving high-quality development of the national economy.However,the risk of spontaneous combustion in coal production,storage and transportation has greatly restricted the development of the coal industry,and the spontaneous combustion of coal also Some geological disasters will be induced,and the study of spontaneous combustion disasters in coal mines is essential for the healthy and orderly development of my country's economy and society.Based on the coal seam fire-fighting treatment project in Bainaimiao Coal Mine,this paper summarizes the conditions,processes and influencing factors of coal spontaneous combustion by consulting the research results of coal spontaneous combustion at home and abroad in recent years,analyzes the causes of coal spontaneous combustion in Bainaimiao Coal Mine,and conducts coal Governance;and through a combination of field investigation,theoretical research and numerical analysis,the strength change of the slope rock mass and the stability of the slope under the influence of spontaneous combustion of the coal seam are analyzed.The limit equilibrium method and the strength reduction method are used to calculate the safety factor of the slope.The distribution characteristics of stress,strain and displacement in the slope before and after spontaneous combustion and after treatment are compared and analyzed under different working conditions.The following researches have been carried out:(1)The low-temperature oxidation of coal and the interaction of moisture with coal usually contribute most of the heat required for spontaneous combustion of coal;(2)the rank of coal is inversely proportional to the spontaneous combustion tendency of coal,low-rank coal has a relatively higher volatile yield,higher oxidation rate,lower ignition point,and the spontaneous combustion process of coal is more likely to develop to the combustion stage;(3)oxygen is a necessary condition for spontaneous combustion of coal,and the oxygen concentration is positively correlated with the oxidation rate;(4)the effect of moisture content on the spontaneous combustion process of coal is twofold,the oxidation rate of coal increases as the water content increases to about 20%,and then decreases as the water content increases;(5)the oxidation rate of coal increases with the increase of ambient temperature,and the heat accumulated by lowtemperature oxidation of coal further promotes the spontaneous combustion process of coal;(6)the oxidation rate of coal decreases as the degree of coal aging increases,but it will not completely drop to zero;(7)the particle size of coal determines the diffusion depth and concentration of oxygen in the coal seam,as well as the surface area of the coal.The smaller the particle size,the greater the oxygen concentration at the same depth,and the larger the contact area between coal and oxygen,and the faster the oxidation rate,which can provide for the oxidation-reduction reaction of coal.More oxygen to ensure the process of spontaneous combustion of coal;(8)the carbon content directly affects the oxidation rate of coal,and the oxidation rate decreases as the carbon content decreases;(9)the slope safety factors under natural conditions and rainstorm conditions before spontaneous combustion of coal seams are 2.08 and 1.323 respectively,which meet the safety requirements of the specification,but the safety factor is lower by 0.7 in comparison,indicating that rainfall has a greater impact on slope stability;(10)after the spontaneous combustion of the coal seam,the physical and mechanical properties of the rock formation in the combustion zone change,the safety factor is 0.712 under rainstorm conditions,and local landslide damage occurs on the slope,but the overall stress distribution of the slope is basically unchanged compared with before the spontaneous combustion,indicating that the coal seam combustion directly caused the landslide damage;(11)after coal mine treatment,a comparative analysis of reinforced and unreinforced slope foot geogrid under rainstorm conditions is carried out,the safety factors are 1.302 and 1.187 respectively,the safety factor of the reinforced slope meets the safety requirements of the specification,it shows that the slope toe is on the most dangerous sliding surface of the slope,geogrid reinforcement can effectively improve the stability of the slope and prevent the recurrence of spontaneous coal combustion disasters,at the same time,it can provide reference for similar coal seam spontaneous combustion and slope treatment projects.