Study On Dynamic Disaster Characteristics And Shock Wave Overpressure Model Of Gas Explosion In Roadway

Gas explosion accidents occur frequently in the process of coal mining.Gas explosion accidents not only cause casualties to workers,but also destroy mine facilities and interrupt ventilation system,thus causing secondary accidents such as roof caving,coal dust explosion,mine fire,roadway collapse,etc.,causing huge property losses and adverse social impacts.Therefore,it is necessary to study the mechanism and protective measures of gas explosion damage to underground roadway.Based on the propagation law of gas explosion and its shock wave damage characteristics,this paper analyzes the evolution characteristics of gas explosion flow field in the roadway,and analyzes the variation law of explosion overpressure,explosion temperature field,explosion velocity field and explosion stress.By means of numerical simulation and theoretical analysis,the influence law of shock wave amplitude,reflected wave,stress wave and duration of gas explosion on roadway buildings is studied.Aiming at the damage mode under the condition of gas explosion,the reflection,superposition effect,attenuation change law of shock wave overpressure of gas explosion in different roadways,the impact law of roadway wall structure and the interaction between gas explosion and roadway wall are studied by ANSYS/LS-DYNA software.The influence of roadway wall size and different explosion energy on roadway wall explosion impact is analyzed.The research results can provide certain theoretical guidance for the design of underground roadway and reduce the loss of gas explosion has important practical significance.It also provides theoretical reference for gas explosion accident investigation,protection and damage assessment.According to the research content,the following conclusions are drawn:First,the evolution law of the gas explosion shock wave flow field is simulated,and it is found that: a.The explosion shock wave continuously changes during the propagation process,which is propagated by the initial spherical wave,and then the area of the shock wave gradually increases,after encountering the wall structure,it extends forward along the wall surface axis.b.There would be irregular distribution in the temperature field of gas explosion.The front temperature of the explosion flow field reaches its maximum at the initial state,and presents a stepped temperature gradient as the reaction proceeds.c.In the pressure field,because of the reflection and superposition of explosive gas in the roadway space,the explosive shock wave overpressure continues to increase until the energy of gas explosion is exhausted,which indicates that the damage caused by gas explosion in the roadway space is more serious.d.In the explosion velocity field,the gas flow will accelerate along the wall,and the gas flow velocity at the opening end is the largest,showing a columnar distribution.The shock wave is accelerated to release along the wall with a certain acceleration,and the gas velocity will fluctuate.Because the gas temperature and pressure are in an unstable state,there will be obvious difference between the open end and the closed end.Second,the damage effect of explosive stress on wall structure is simulated.The blast shock wave has experienced the propagation from air and the stress transfer from the initiation to the wall structure of roadway.The wall structure is still damaged under the continuous action of internal stress wave,resulting in the overall instability of the wall structure of roadway.Among them,there are many peaks in the overall change of stress and load,showing the phenomenon of ups and downs oscillation and fluctuation.In the later stage,the stress load has a great influence on the structure,showing a continuous progressive failure process.At last,the impact model of explosion overpressure in roadway is analyzed,and the influence of different conditions on the change of explosion overpressure is studied by using the model.The results show that the curved edge of explosion overpressure varies with different explosion energies,resulting in two peaks of overpressure,and the first arrival rate of overpressure is greater than the second peak rate.In addition,the influence of wall thickness on overpressure is also analyzed.The thinner the wall thickness is,the more vulnerable it will be to damage.The smaller the wall thickness is,the larger the peak value of overpressure on the wall structure will be.Under the condition of certain explosion intensity,the explosion energy will continue to decrease,and will increase with the increase of thickness.The overall trend of overpressure variation of explosive shock wave at different locations is not very different,but the overpressure value near the explosive source varies greatly.When the explosive shock wave is far from the explosive source,the peak value of overpressure will be slower.Finally,with the decrease and loss of explosive energy,all measuring points tend to be fixed.Finally,the non-linear relationship between overpressure and distance of explosive shock wave is obtained by fitting.