公路隧道施工压入式通风流场及瓦斯分布规律研究

摘要

The press-in type ventilation is a ventilating method that is more adopted in tunnel construction. In order to research flow fields and gas distribution laws of press-in ventilating in construction with the gas tunnel bench cut method,this paper establishes a three-dimensional model by means of fluid mechanics software Fluent and performs numerical simulation,compares different setting distances from the air outlet of local fans and lower step surfaces and flow fields under the setting forms,and analyzes the influences of setting locations of local fans on distribution of gas concentration and air flow speed.The result of simulation show that under the condition of the same inlet speed,the further the local fans are from lower step surfaces,the more the gas concentration at frontal section of forward flow zone,the smaller the range of high-concentration gas area in recirculation zone,but the more the maximum concentration;and arrangement of local fans and air ducts on opposite sides can balance gas distribution in upper and lower step sections.This research provides a theoretical basis for putting forward the ways of improving ventilating effect.%压入式通风是隧道施工中采用较多的通风方法。为研究瓦斯隧道台阶法施工压入式通风流场及瓦斯分布规律，利用流体力学软件 Fluent 建立隧道三维模型并进行数值模拟，对局扇出风口与下台阶面不同布设距离及布设形式下流场进行对比，分析局扇布设位置对瓦斯浓度、风流速度分布的影响。模拟结果表明：在相同的入口速度条件下，局扇距离下台阶面越远，射流区迎头断面瓦斯浓度越大，回流区中高浓度瓦斯区域范围越小但最高浓度越大；局扇与风管异侧布设能平衡上下台阶区段内瓦斯分布。该研究为提出改善通风效果的途径提供理论依据。