机械通风及地温对寒区隧道防冻长度的影响

Effect of Mechanical Ventilation and Ground Temperature on Anti-Freezing Length of Tunnels in Cold Regions

为揭示通风参数及地温对寒区隧道冻害的影响,基于传热学理论推导了隧道围岩-衬砌-风流三维非稳态数值传热控制方程,分析了不同节点的数值传热差分方程,建立了高地温寒区隧道三维温度场数值计算模型;基于数值分析研究了机械通风速度、机械通风时间和地温对高地温寒区隧道防冻长度的影响.结果表明:1)不考虑机械通风,孜拉山隧道的防冻长度超过1200 m;地温每升高5℃隧道防冻长度将减小约100 m.2)考虑机械通风影响,当地温为10~30℃时,每天以2.5 m/s的速度通风2.0 h可减少防冻长度215 m;不同地温下机械通风速度每增大0.5 m/s,防冻长度减小约20 m,地温对防冻长度衰减速率影响很小;当机械通风时间小于2.0 h时,不同地温条件下增大机械通风速度对防冻长度的影响不大.

In order to reveal the effect of ventilation parameters and ground temperature on freezing damage in tunnels in cold regions,the three-dimensional unsteady numerical heat transfer control equations for the tunnel surrounding rock,lining,and airflow are developed based on heat transfer theory.The numerical heat transfer difference equations of different nodes are analyzed,and a three-dimensional temperature field numerical calculation model is established for tunnels in cold regions with high ground temperatures.The effect of mechanical ventilation velocity,mechanical ventilation time,and ground temperature on the anti-freezing length of tunnels in cold regions with high ground temperatures is studied based on numerical analysis.The results show that 1)without considering mechanical ventilation,the anti-freezing length of Zilashan tunnel will exceed 1200 m and decrease by about 100 m when the ground temperature increases by every 5℃.2)By considering the effect of mechanical ventilation,when the ground temperature is 10–30℃,ventilation at a speed of 2.5 m/s for 2.0 h per day can reduce the anti-freezing length by 215 m;the anti-freezing length decreases by about 20 m as mechanical ventilation velocity increases every 0.5 m/s under different ground temperatures,and the effect of ground temperature on the decay rate of anti-freezing length is slight;when the mechanical ventilation time is less than 2.0 h,increasing mechanical ventilation velocity under different ground temperature conditions has little effect on anti-freezing length.