压入式通风施工隧道内空气流动方向和速度研究

Study on the Direction and Velocity of Air Current inside Tunnelling under Condition of the Forced Ventilation

对压入式机械通风夏季施工隧道内空气流动方向和速度进行了调查。结果显示：隧道内空气流动呈非单一方向，隧道顶部风速最大，离地面２ｍ～３ｍ处风速最小，并且在距洞口３００ｍ处存在气流交叉现象，其原因可能是隧道内热负压自然通风和洞外气温较高两者共同作用所产生。

he paper reports the study on the direction and velocity of air current inside construction tunnel under condition of ventilation with fan.The result shows that the direction of air current is not one way.The direction in the upper part of tunnelling is opposite to that in the lower of tunnelling.The velocity in the top of tunnelling is the fastest.Besides there is a intersection of air current at 300 meters apart from entrance of tunnelling.It is considered that reason of intersection of air current is two conditions jointly.The one is that nature ventilation due to the heat pressure is caused by high air temperature in excavatimg face.The other is that the heated air current outward is resistted which is caused by air temperature outside tunnelling being higher than in middle section of tunnelling