考虑开挖过程的瓦斯隧道施工通风影响机制——以鸡鸣隧道为例

为研究瓦斯隧道开挖过程中通风设备布置对通风效果的影响机制,以城开高速鸡鸣隧道为研究对象,考虑风筒直径、出风口与掌子面距离、风筒高度三个因素,基于数值模拟方法,进行三因素三水平正交试验；以瓦斯平均浓度数据为基础,研究了瓦斯浓度在施工通风影响下的分布特点,通过极差分析和方差分析研究了9种布置方案下三个因素对三种施工情况下通风效果的影响。研究结果表明：上掌子面顶角、底角及下掌子面底角处,瓦斯分布较为集中,实际施工过程中应加强对该区域的监测；回风侧瓦斯浓度高于进风侧。不同的施工情况下,三个因素对通风效果的影响程度存在差异；即在整体掌子面或仅有上掌子面施工的情况下,三个因素对通风效果的影响程度从大到小依次为：风筒高度、风筒直径、出风口与掌子面距离；仅有下掌子面施工时则依次为：风筒直径、风筒高度、出风口与掌子面距离。在本文研究结论的基础上,提出针对台阶开挖过程中可能出现的不同工况下的以提高通风效率为目的的通风设备布置建议。

Considering the impact of ventilation in gas tunnel construction

To research the mechanism of the ventiduct layout on ventilation effect in the gas tunnel during excavation, basing on the research of Ji-ming Tunnel of Cheng-kai Expressway, considering three factors, which are the diameter of duct, the distance between ventiduct and working face, and the height of duct. Three factors and three levels of orthogonal test were applied based on numerical simulation. According to the data of average gas concentration, this paper studies the distribution characteristics of gas concentration under the influence of construction ventilation, and researches the influence of three factors on ventilation effect under three conditions of nine layout schemes by range analysis and variance analysis. The research shows that: the gas distribution is concentrated at the top and bottom angle of the upper face and the bottom angle of the lower face; So, the monitoring should be strengthened in the process of construction. Gas concentration in return side is higher than that in intake side. For different conditions, the degree of three factors on ventilation effect is different; Under the condition of construction of integral and upper working face, the sequence of degree of three factors on ventilation effect is: the height of duct, the diameter of duct and the distance between ventiduct and working face; When only the lower one is constructed, the order turns into: the diameter of duct, the height of duct and the distance between the duct and working face. On the basis of the research conclusions, some suggestions on ventiduct layout aiming at improving efficiency under different conditions during bench excavation are raised.