| In recent years,with the increasing of coal mining depth and intensity,the disaster of spontaneous combustion of coal in goaf has become more and more serious,especially for high gas flammable coal seam.Existence of increasing the safety of the gas at the same time,it will reduce the safety of spontaneous combustion,on the contrary,reduces the risk of spontaneous combustion at the same time can not meet the requirements of safe gas drainage,easily lead to two kinds of potential safety problems of one sector of imbalances.Based on willow mine experimental working face as the research object,through the experiment test,numerical simulation,field observation and theoretical analysis,the mechanism of coal spontaneous combustion in goaf of high gas and easy spontaneous combustion is studied,provide theoretical basis for the safety of the mine's daily production.The main conclusions of this paper are as follows:(1)The presence of rock bed can be determined through laboratory covers the basic physical parameters of coal seam gas and spontaneous combustion tendency,it is concluded that the coal seam spontaneous combustion tendency level are class II easy spontaneous combustion of coal seam,and thermal metamorphism of magma intrusion makes the metamorphic grade of coal,to promote the growth of the pore structure of coal seam,improve the ability of adsorption of coal seam and gas reservoir.(2)Use of 3 dec numerical simulation the fracture of overlying strata of mined-out area,and on the basis of establishing goaf three-dimensional geometric model,and using numerical simulation software comsol simulation of three-dimensional stress,porosity and permeability distribution of the mined-out area,found regarding the original stress,postharvest stress,porosity and permeability distribution are similar,but after the intrusion of magmatic rocks form occurs in hard rock bed above the coal seam,and the bedrock itself has the characteristics of hard and not easily broken,to some extent as the role of key stratum of mine,the supporting effect of the hard rock bed for the overburden rock effectively bears the gravity of overburden before breaking,hindered the passing down of stress,cause the lower part of the upper coal seam and rock bed between the accumulation of coal or rock loose,crack channel,goaf compaction degree is reduced,porosity and permeability are increased.(3)Based on the research on stress,porosity and permeability,the distribution characteristics of the flow field and the distribution range of spontaneous combustion are compared and analyzed,and supplemented by field observation as the validation,it is concluded that the numerical simulation is reliable,and the spontaneous combustion zone and the distribution of gas concentration field can be used to guide the practice.At the same time,analyzed the influence of the distribution range of spontaneous combustion zones of subsurface coal bed in rockbed,with the different different air supply,concluded that with the increase of air quantity,three zones distribution scope expanding gradually,moves away from the working face and towards the deep of goaf.(4)In view of the working face goaf spontaneous combustion characteristics,the rear built "gel plugging,foam cover,inert gas lean oxygen" means of comprehensive fire prevention,as well as "note glue,buried tube intubation to idle and injection,drilling to idle and injection dip" infusion technology,the combination of fire-fighting media was carried out on the left coal mined-out area "stereo coverage,inerting" fast,effective prevention and control of goaf coal spontaneous combustion. |
PDF Full Text Request