Study On The Energy Distribution Characteristics Of Gas Explosion And The Destructive Effect Of Thermal Shock

At present,China’s energy source is mainly coal,and in the process of coal mining,gas explosion,as the most serious coal mine safety accident,will cause a large number of casualties and property losses,and even affect the country’s economic development.Therefore,it is of certain reference value to explore the energy transformation law of roadway gas thermal explosion and the damage mechanism of roadway wall under thermal impact,and to the anti-explosion design of underground roadway and reduce the impact of gas explosion disaster,and to provide theoretical reference for the accident investigation,protection and damage evaluation of underground gas explosion.In this paper,the reaction conditions and influencing factors of gas explosion in roadways,the propagation characteristics of shock wave and flame wave,the energy distribution of thermal explosion and the failure characteristics of roadway wall are analyzed.Based on the theoretical analysis,the physical and mathematical models of gas explosion in roadways are established,and the numerical model of mine roadways is established by combining with the numerical simulation analysis software ANSYS/LS-DYNA.The distribution of temperature field,thermal stress field and its influencing factors,attenuation law of blast wave,dynamic response and deformation process of roadway wall,and the influence of different heat release rate on gas explosion in roadway are studied.The damage state of the roadway wall under different breaking energy is simulated,and the proportion of breaking energy of the roadway wall is determined by investigating the actual gas explosion accident.The main conclusions are as follows:1.On the basis of equivalent TNT equivalent method,the discrete detonation source model is proposed.By comparing the numerical simulation analysis with the single detonation source model,and comparing the simulation results with the actual tunnel test results,it is found that the discrete detonation source model can overcome the shortcomings of too much pressure and too fast decay rate near the initiation point under the single detonation source model,which is more consistent with the relevant test results.2.The thermal shock wave generated after the gas explosion acts on the roadway wall,which increases the internal temperature of the coal and rock on the roadway wall and damages the coal and rock on the wall.In this process,the energy is gradually dissipated,thus reducing the forward propagation energy of the thermal shock wave.By gas explosion overpressure distribution formula is derived and the temperature distribution in the formula,it is concluded that roadway gas explosion in the shock energy and heat energy of time and space distribution rule: the square root of the intensity of gas explosion shock wave and its diffusion distance x is inverse proportion,and its diffusion length x and its diffusion time t is directly proportional to the cube root of the square.The distribution of heat energy is closely related to impact energy.3.Compared with the gas explosion in the roadway under 5 different heat release conditions,the higher the temperature of gas explosion release,the lower the intensity of shock wave will be.The intensity of gas explosion shock wave and the dynamic response of roadway wall are inversely proportional to the heat release rate.In terms of time,the influence of heat release rate in the early stage of gas explosion is greater than that in the late stage,and the influence gradually decreases with the passage of time.In the spatial dimension,the influence of different heat release rates on gas accumulation area is greater than that on air area,and the influence gradually decreases with the increase of roadway length.4.A large amount of energy released instantly by the gas explosion is transmitted into the coal and rock through the wall of the roadway.In the process of transmission,most of the energy is dissipated to form a failure zone in the wall crushing process,and the remaining energy gradually forms a fracture zone in the coal and rock with the shock wave.