压入式通风条件下高地温隧道降温效果研究

Study on Cooling Effect of High Ground Temperature Tunnel Under Forced Ventilation

为分析压入式通风对高地温隧道的降温效果,基于典型双线铁路隧道建立三维计算模型,重点研究风速、风温、岩温、风管出风口与掌子面间距及风管布置对降温效果的影响,并与理论计算结果进行了对比。结果表明:掌子面附近存在涡流现象,有利于局部温度降低,随着风流远离掌子面,逐渐向层流过渡,隧道平均温度也逐渐升高;风速越高,隧道内温度越低,温度场越均匀,越能快速达到温度稳态;风温越低,隧道温度也随之降低,且降温效果较提高风速更显著;围岩温度越高,隧道内空气温度越高,且通风对围岩温度场的影响深度十分有限;风管与掌子面间距越大,通风后隧道温度越高,施工中应及时跟进风管,以最大程度降低隧道温度,而风管布置对降温效果影响不大;理论分析较数值计算得到的温度场沿隧道纵向温度分布均匀性更差;总体来看,采用压入式通风可有效降低隧道内温度,风速20m/s、风温14℃时,降温率可达66%。

In order to analyze the cooling effect of high ground temperature tunnel under forced ventilation,a 3D simulation model was established based on typical double track railway tunnel.The influence of wind speed,wind temperature,rock temperature,distance between air outlet and heading face,and ventilation pipe layout on the cooling effect was studyed,and the results were compared with theoretical calculations.The results show that there is vortex near the heading face,which is conducive to local temperature reduction.As the wind moves away from the heading face,it gradually transitions towards laminar flow,and the average tunnel temperature also increases.The higher the wind speed is,the lower the tunnel temperature becomes with more uniform temperature field,and the faster it can reach a stable temperature state.The lower the wind temperature is,the lower the tunnel temperature becomes,and the cooling effect is more significant than increasing the wind speed.The higher the rock temperature is,the higher the tunnel temperature becomes,and the influence depth of ventilation on the temperature field of surrounding rock is very limited.The larger the distance between outlet and heading face is,the higher the tunnel temperature becomes after ventilation.Therefore,the air outlet should be followed up in a timely manner to minimize the tunnel temperature.However,the ventilation pipe layout has little impact on the cooling effect.The uniformity of temperature distribution along the longitudinal direction is worse in theoretical analysis compared to numerical simulation.Overall,forced ventilation can effectively reduce the temperature inside the tunnel.When the wind speed is 20m/s and the wind temperature is 14℃,the cooling rate can reach 66%.