The Failure Mechanism Of Anti-reflux Device Causedby Power Of Coal And Gas Outburst

In order to prevent gas backflow after the outburst,fluid mechanics was used to analyze the failure mechanism of shock wave to the backflow prevention device of ventiduct and anti-reflux damper.Based theoretical derivation,the shock wave propagation model of coal and gas outburst conditions was obtained,the reflex overpressure acting on the anti-reflux damper and backflow prevention device of ventiduct was given.Used the coal and gas outburst energy propagation simulation and parameter determination test device system,simulated the propagation of shock wave in the ventilation system when coal and gas outburst disasters occur and shock wave damaged to the anti-reflux damper and backflow prevention device of ventiduct.The results showed that the actual shock wave attenuation is faster than numerical simulation and theoretical calculation,the experimental and simulation errors are not big and the overall trend of change is same,the reflected shock wave overpressure propagation law is consistent,it is feasible to use numerical simulation to study the propagation and attenuation of shock waves.On this basis,used FLUENT to establish a numerical model,Simulated the propagation of shock waves in the roadway under four different outburst conditions.And inputed the data of the overpressure changes with time at the anti-reflux damper and backflow prevention device of ventiduct into LS-DYNA.Numerical simulation study on the failure mechanism of the anti-reflux damper and backflow prevention device of ventiduct based on the parameters of the physical experiment device.It is found that the peak value of shock wave overpressure at the backflow prevention device of ventiduct is greater than the position of the anti-reflux damper.The shock wave overpressure at the backflow prevention device of ventiduct oscillated down after the first crest appeared,but the shock wave overpressure peak at the position of the anti-reflux damper appeared at the second crest.This is because the shock wave is blocked by the backflow prevention device of ventiduct and forms a reflected wave,enter the tunnel again from the ventiduct,the reflected wave arrives at the anti-reflux damper position and the original shock wave overpressure is superimposed.Considering that the backflow prevention device of ventiduct is not damaged,the shock wave overpressure at the damper is about 20.5%-23.9% larger than the unconsidered.At the same time,the larger the outburst pressure and the outburst aperture,the larger the corresponding shock wave overpressure peak.Existing specifications of anti-reflux damper and backflow prevention device of ventiduct are unable to resist the shock wave overpressure under0.74 MPa outburst pressure,the maximum stress exceeds the yield limit of the respective materials,and the material and structure need to be improved.Based on the above analysis,the material and structure of the air door and air tube backflow prevention device are improved,and the LS-DYNA software is used to simulate the structural damage of the improved air door and air tube backflow prevention device.The dynamic characteristics of the countercurrent device.The study have showed that: under the pressure of 2MPa,the Q460 steel anti-backflow damper with a thickness of 25 mm and the structure-reinforced air duct anti-backflow device with a thickness of 25 mm can resist i MPact power;the improved structure of the 25mm-thickness damper and anti-backflow device can work in the worst conditions The lower maximum stress is less than the yield limit of the material,and the maximum deformation is much less than its own thickness,which can meet the safety requirements and the improvement plan is reasonable.