特长大断面瓦斯公路隧道风险大,施工通风是隧道建设的“生命线”。以在建贵州公路第一隧—桐梓隧道为工程背景,综合考虑瓦斯涌出量、爆破炮烟、工作最多人数、作业机械以及最小风速,分别计算压入式通风和巷道式通风需风量、风压及风机功率,分析了风管直径对通风阻力的影响规律,并对2种方案瓦斯浓度和风速进行了数值分析,最后比较2种方案的经济性。结果表明:原设计压入式通风方式未考虑非煤系地层瓦斯涌出而无法满足施工通风要求;风管直径对通风阻力影响显著,结合工程实际选用1.8 m风管直径;数值分析表明,压入式通风断面最大瓦斯浓度始终高于巷道式,巷道式通风的瓦斯浓度比压入式通风提前进入稳定区随后趋向于0,巷道式通风的速度稳定区的值比压入式通风高2~2.5倍;巷道式通风方式相比压入式通风,设备投入和运营费用均较低,经济性更优。研究成果具有典型代表性,可为隧道施工通风提供理论指导和工程参考。
The extra-long and large highway tunnel with high gas has great risk, and ventilation is the "lifeline" of tunnel construction. Based on the Tongzi Tunnel, the first tunnel on Guizhou highway under construction, taking into account gas emission, blasting smoke, the maximum number of workers, operating machinery and minimum airspeed, the air requirements, air pressure, and fan power for forced ventilation and gallery ventilation are compared and calculated. The influence of air duct diameter on ventilation resistance is discussed. The gas concentration and wind speed of the two schemes are numerically analyzed. Finally, the economy of the two schemes is compared. The results show that: The original design of forced ventilation cannot meet the construction ventilation requirements without considering the gas emergence from non-coal strata. The diameter of the duct has a significant influence on the ventilation resistance, and the 1.8 m duct diameter is chosen in combination with the actual project. Numerical simulation analysis shows that the maximum gas concentration of the forced ventilation is always higher than that of the gallery ventilation, and the gas concentration of the gallery ventilation will enter the stable area earlier than the forced ventilation and then tend to 0. The value of the speed stabilization area of the gallery ventilation is 2~2.5 times higher than that of the forced ventilation. Compared with forced ventilation, the gallery ventilation mode has lower equipment input and operating costs and better economy. The research results are typical and can provide theoretical guidance and engineering references for tunnel construction ventilation.
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