突出冲击波对风筒防逆流装置的破坏失效研究

Failure mechanism of anti-backflow device for the ventiduct under shock wave of coal and gas outburst

为分析煤与瓦斯突出事故中风筒防逆流装置的安全性,研究了现有防逆流装置在10MPa煤层瓦斯压力规模的突出冲击波超压作用下的动力学特征,并且基于研究结果和安全设计理念给出改进方案。结合流体动力学,得到了巷道不同位置的冲击波超压数学模型,并运用LS-DYNA软件对冲击载荷下的风筒防逆流装置结构破坏进行数值模拟,得到不同结构和材料的风筒防逆流装置的动力学特征。研究表明:风筒截面积远小于巷道截面积,由于传播路径截面积的缩小,从巷道进入风筒的冲击波超压会突然增大至巷道中的五倍。现有的防逆流装置在10MPa煤层瓦斯压力规模的冲击波超压作用下最大应力值达到664MPa,远大于Q235钢的屈服极限235MPa,无法满足安全要求;结构改进后的25mm和30mm厚度防逆流装置,在最恶劣工况下最大应力均小于材料的屈服极限,最大变形远小于自身厚度,可以满足安全要求。

In order to analyze the safety of the anti-backflow device for the ventiduct in the coal and gas outburst accident, the existing anti-backflow device was studied, and its dynamic characteristics under the outburst shock wave overpressure of 10 MPa coal seam gas pressure, and an improvement plan was proposed based on the research results and safety design concepts.Combining with fluid dynamics, the mathematical model of shock wave overpressure at different positions of the roadway was obtained.According to the corresponding regulations and actual safety requirements of the coal industry, the LS-DYNA software was used to simulate the structural damage of the ventiduct anti-backflow device under the impact load.Dynamic characteristics of the anti-backflow device of steel ventiduct of different structure and material was obtained.Research shows that the cross-sectional area of the ventiduct is much smaller than the cross-sectional area of the roadway.Due to the reduction of the cross-sectional area of the propagation path, the overpressure of the shock wave entering the ventiduct from the roadway will suddenly increase to five times of that in the roadway.The maximum stress of the existing anti-backflow device under the shock wave overpressure of 10 MPa coal seam gas pressure scale reaches 664 MPa, which is far greater than the yield limit of Q235 steel of 235 MPa, and cannot meet the safety requirements;maximum stress of the improved structure of the 25 mm and 30 mm thickness anti-backflow device under the worst conditions is less than the yield stress of the material, and the maximum displacement is much less than its own thickness, which can meet safety requirements and the improvement plan is reasonable.