Research On A New Circular Insulation Blind Ditch Antifreeze Technology For Railway Tunnel In Cold Region

In China,the cold region covers a wide area,cold and traffic construction scale increases gradually,more and more cold regions tunnel number,resistance to cold and tunnel antifreezing problem increasingly cause the attention of people.There is a problem that the tunnel in the cold area can not get a good effect of thermal insulation and anti-freezing even after the application of complete thermal insulation and anti-freezing measures.Investigate its reason,the first is not clear all kinds of weather,engineering cold regions tunnel under the condition of temperature field distribution characteristics,for railway tunnel,the train wind also cannot ignore temperature field in tunnel,the second cold regions tunnel fortify the lack of necessary theoretical basis of the selection of length,length of fortified shortage caused by cold injury,at the same time there are caused by drainage system is easy to freeze tunnel insulation anti-freezing measures,solve the problem of the lack of corresponding heat preservation and drainage combined with antifreezing measures.Therefore,it is urgent to explore the law of temperature field of tunnel in cold area under different conditions,make clear the reasonable length of tunnel fortification in cold area,and study a new anti-freezing measure to prevent the freezing of drainage system,which is of great significance to prevent the freezing damage of tunnel in cold area.Therefore,this paper combined with xinjiang’s railway tunnel project on arjin mountain,mainly from the train under the action of the piston wind cold regions tunnel temperature field,the length of antifreeze fortification criteria and new blind ditch of toroidal insulation antifreezing measures from three aspects,mainly includes the following three aspects:1.Based on the basic principles and methods of heat transfer and fluid mechanics,the theoretical calculation model of temperature field in cold tunnel is derived,and the effects of ventilation and surrounding rock conditions(inlet airflow,surrounding rock temperature and surrounding rock thermal conductivity)on the distribution of temperature field in tunnel are explored.According to the theory of wind-solid coupling,the fluid-solid coupling heat transfer model of the wind-surrounding rock of the train was established,and the change rule of the longitudinal and transverse temperature of the tunnel in the cold region under different train speeds and intervals was defined.2.Based on the condition that there is no drainage pipe freezing in the lining layer and no frost heave in the surrounding rock,the selection standard of the fortification length is given based on the freezing temperature rule of the surrounding rock in the cold tunnel.The method of temperature prediction in tunnel under ventilation and surrounding rock conditions is established,and the fortification length of tunnel in cold area is determined according to the selection criteria of fortification length.3.Put forward a new type of blind ditch of toroidal insulation anti-freezing measures,blind ditch of ring is given to the insulation design parameters and construction methods,and through the field application of the tunnel on arjin mountain,verify the toroidal insulation can realize blind ditch the tunnel portal segment lining drainage unobstructed.In this paper,the distribution law of temperature field of tunnel in cold area under different conditions(train wind,ventilation,surrounding rock)is proved,the problem of lack of theoretical basis for the selection of tunnel defense length in cold area is solved,and a new circular insulation blind ditch measure combining heat preservation and drainage is put forward,which is of great significance to the prevention of freezing damage of tunnel in cold area.