隧道掌子面施工风管布设方式对稀释瓦斯效果影响研究

Research on the Effect of Air Duct Arrangement on Gas Dilution of Gas Tunnel

以成贵铁路白杨林隧道为研究对象,对瓦斯隧道施工压入式通风效果进行分析,利用CFD流体动力学软件,建立模型并进行数值模拟计算,得到不同风管出口距掌子面距离下,隧道内风速流场和瓦斯浓度的分布规律,并与现场测试数据进行对比,优化流场分布,减少瓦斯在掌子面附近积聚的现象。计算结果表明:一定风速条件下,风管末端距掌子面距离直接影响施工通风效果和掌子面瓦斯浓度分布。风管末端距离掌子面越大,稀释瓦斯效果越差,掌子面瓦斯积聚现象越严重。单侧风管通风情况下,掌子面瓦斯稳定浓度为0.07%,瓦斯浓度随风管末端距掌子面的增加而升高。根据白杨林隧道瓦斯溢出和施工通风情况,得出其风管末端距掌子面距离为13m可使瓦斯不形成聚集,保证施工安全。

With reference to Baiyanglin tunnel on Chengdu- Guiyang Railway,the pressed ventilation effect on gas tunnel construction is analyzed. The flow field and gas distribution law in different distances from the air duct outlet to the heading face are calculated with CED fluid dynamics software and model numerical simulation. The simulation results are compared with the field test values to optimize flow field and minimize gas accumulation at the heading face. The results indicate that the distance from air duct outlet to heading face imposes direct effect on the ventilation and gas distribution at certain wind speed.The gas diluting is getting less effective and the gas accumulation heavier at the heading face as the distance from air duct outlet to heading face increases. The gas concentration value is stable at 0. 07%when the air duct is installed on only one side of the tunnel. The gas concentration increases with the increase of the distance from the air duct outlet to the heading face. According to the gas tunnel of Baiyanglin,it is concluded that where the distance is 13 m,there is no gas accumulation and normal construction is ensured.