列车活塞风对寒区铁路隧道温度场的影响

Impacts of Train Piston Wind on Temperature Field of Railway Tunnel in Cold Regions

研究目的:列车通过隧道会产生活塞风,活塞风会将寒区隧道洞外冷空气带入洞内,导致洞内温度场分布发生变化,若对这种影响认识不到位,会导致洞内抗防冻措施不合理造成冻害发生,影响隧道运营安全。鉴于此,采用理论分析和数值模拟等方法,分析列车活塞风对隧道洞内温度场的影响机制,研究列车活塞风对寒区特长铁路隧道洞内温度场的影响规律,为寒区隧道抗防冻设计提供技术支撑。研究结论:(1)冬季列车通过隧道后,活塞风会引起洞内温度场在短时间内显著变化,列车活塞风对洞内温度场持续影响时间较短,列车通过后,洞内温度场会逐渐恢复,特别是当列车频次较小时,基本可恢复到自然通风条件下状态;(2)行车频次导致洞内纵向负温长度增大或减小率均在1%左右;随着围岩温度的增大,隧道洞内纵向负温长度显著降低,且围岩温度越高,活塞风作用方向对洞内温度场影响越小;(3)考虑活塞风对寒区隧道防寒抗冻影响时,应重点考虑其对两侧水沟抗防冻的影响;由于局部衬砌会出现交替冻融现象,隧道结构设计时,应对衬砌耐久性做一定的考虑;(4)本研究成果可供寒区特长铁路隧道建设参考,特别是单向自然风条件下铁路隧道抗防冻设计。

Research purposes:The piston wind will be generated when the train passes through the tunnel and the piston wind will bring the cold air into tunnel,resulting in the changes of temperature field in tunnel.If the understanding of the impacts is improper,the unreasonable fortification measures will be taken and the freezing damages will occur,which have serious impacts on the safety of train operation.In view of such circumstances,the impacting mechanism of train piston wind on temperature field in tunnel was analyzed by theoretical analysis and numerical simulation,and the impacting law of train piston wind on temperature field in tunnel in cold regions was studied,which provided a technical support for the anti-freezing design of tunnel in cold region.Research conclusions:(1)The piston wind will cause the significant changes of temperature field in tunnel instantly while the train passes through the tunnel in winter.The continuously impacting of train piston wind on the temperature field in tunnel is shorter.After the train passes,the temperature field inside the tunnel will gradually recover,especially when the frequency of the train is small,it can basically return to the state under natural ventilation conditions.(2)The frequency of driving causes an increase or decrease in the longitudinal negative temperature length inside the tunnel,with a rate of about 1%.With increasing of surrounding rock temperature,the longitudinal negative temperature length in tunnel significantly decreases.The higher the surrounding rock temperature is,the weaker the impacts of piston wind direction on the temperature field in tunnel becomes.(3)Considering the impacts of piston wind on the cold and frost resistances of tunnel in cold regions,the impacts on anti-freezing of ditches at both sides of tunnel shall be focused.Due to the occurrence of alternating freeze-thaw phenomena in local lining,the durability of the lining should be taken into consideration in the design of tunnel structures.(4)The research results can be used as references for the construction of extra-long railway tunnel in cold region,especially for the anti-freezing design of railway tunnel under the condition of unidirectional natural wind。