高瓦斯隧道施工通风方案设计及瓦斯运移规律研究

Ventilation Design and Gas Migration Analysis of the High-level Gas Tunnel

通风是防治隧道瓦斯浓度超限及爆炸事故的关键措施。以石黔高速公路七曜山隧道为背景,阐述双洞高瓦斯隧道射流巷道式通风方案的设计方法,基于FLUENT软件研究隧道内部风速与瓦斯浓度的分布规律。研究结果表明:内燃机械尾气为七曜山隧道需风量的主控因素,排风洞风筒在横通道弯折处的阻力达到总阻力的21.7%,应注意保持风筒圆顺度;同一断面不同位置风速各不相同,远离风筒的拱顶与拱壁相交处、横通道与正洞连接处等位置积聚;隧道纵向瓦斯浓度在风筒出口附近呈两端高、中间低的分布特征,建议施工人员尽量在风筒出口的后方附近驻足。

Ventilation is the key measure to prevent the gas concentration exceeding the limit and explosion accident.The design method of gallery-used ventilation scheme for double-hole high-level gas tunnel was elaborated,in the Qiyaoshan Tunnel of the Shizhu-Qianzhong Expressway.Based on FLUENT software,the distribution law of wind speed and gas concentration in different spatial positions of tunnel was also analyzed.The results are as follows.Mechanical waste gas is the main control factor of the required ventilation quantity in Qiyaoshan Tunnel.The resistance of the air duct at the bend of the cross passage reaches 21.7%of the total resistance,hence attention should be paid to maintaining the roundness of the air duct.The wind speed in different positions of the same section is different.The gas is easy to accumulate in the central floor of the tunnel,the intersection of the vault and the arch wall far away from the air duct,and the joint between the cross passage and the main tunnel.The distribution characteristics of gas concentration near the outlet of air duct are high at both ends and low in the middle along the longitudinal direction of the tunnel.It is suggested that the construction personnel should stop at the rear of the air duct outlet when resting.