The damages of railway tunnels in cold regions caused by freezing not only jeopardize the stability of the tunnel structures,but also bring huge potential safety hazards to the safe operation of the railways.The freezing-induced damage has always been a challenge and a hot research topic for tunnels in cold regions.The engineering community urgently needs reliable and efficient engineering technical measures in aspect of frost-proofing and anti-freezing.In this paper,the railway tunnels under construction or in operation in cold regions in China are investigated,and the common freezing-induced damages of tunnels,including the cracking and spalling of the lining,the icicles on the tunnel crown,the ice accumulation in the track bed,and the freezing of the drainage system,are summarized and analyzed;then,in view of the three technical difficulties including the lack of the prediction method for the spatiotemporal distribution of the temperature fields of the tunnels,the unclear mechanism and evolution of the freezing-induced damages of the tunnels,and the immature design method and treatment technology for frost-proofing and anti-freezing,the research results obtained so far are summarized and discussed.The relevant achievements are as follows:(1)The indoor experimental system for tunnels in cold regions is developed;the spatiotemporal distribution pattern of the temperature fields is obtained on the basis of the extensive temperature field data measured;the temperature field prediction method is established.(2)The seepage experiment equipment is developed,the chain-type mechanism of the freezing-induced damage is unveiled,and the freezing pattern and the freezing-thawing response mechanism of the drainage system are identified.(3)The design standard for the frost-proofing and anti-freezing of the railway tunnels in cold regions is established,and a comprehensive prevention and control system for the freezing-induced damages of tunnels is formed.Finally,the development direction of further researches on the frost-proofing and anti-freezing of the railway tunnels in cold regions is prospected,including the frost-proofing and thermal-insulating materials,the active thermal-insulation system,and the temperature field prediction.
railway tunnel in cold regionfreezing-induced damage of tunnelprediction of temperature fieldmechanism of freezing-induced damagefrost-proofing and anti-freezing technology
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