Research On Temperature Field Distribution And Frost Protection Technology Of Railway Tunnel In Cold Region

With the rapid development of China’s infrastructure construction, the number of tunnels in cold area has increased; meanwhile, the disease of tunnel has become increasingly prominent and has become a difficult problem concerned by the engineering circles. In the past 20 years, although the scholars have systematically studied the temperature field distribution of tunnel and frost protection technology and put forward a lot of practical value of the theory and methods which provide the basis for the anti freezing design and construction of tunnel in cold region. However, because of the differences in the geographical position, the engineering geological conditions, the complex environment and the level of construction technology, there are still many issues that are worthy of further study. Therefore, with the methods of literature review, field monitoring, numerical simulation, field practice summary, taking Houanshan Tunnel as the research background and selecting test section, we systematically studied the temperature field distribution, frost protection technology of waterproof and drainage, prevention and control of primary support, etc. research results and conclusions are as follows:(1) Through installing thermometers in typical sections of Houanshan Tunnel, we obtain the temperature field distribution of surrounding rock and the vertical temperature distribution before and after tunnel holing-through which provide theory guidance for avoiding freezing injury. The test results show that the maximum temperature difference of insulation board is 9.21 ℃, therefore, the insulation board can play a very good effect of heat insulation. In the range of 200 m from the portal, laying 5 cm thick insulation board may still produce freeze injury.Taking Houanshan Tunnel as the object and establishing calculation models with ABAQUS, we discuss the effect of insulation layer thickness on the temperature field and frost penetration length before and after tunnel holing-through. Numerical simulation results show that the frost penetration length should be 720~830 m after tunnel holing-through.(2) In order to obtain the waterproof and drainage effect of deeply buried ditch, from subgrade export of buried ditch, we deployed 8 suspension temperature hygrometers. After the testing of more than one year, we obtain the temperature distribution of deeply buried ditch. And with the help of ABAQUS, the relationship between the ditch depth and frozen depth is studied. The results of the study show that, buried depth of 3.7 m under the rail ditch can completely prevent the occurrence of freezing phenomenon.(3) According to the phenomenon that initial support is easy to damage, taking Houanshan Tunnel as the background, firstly, analyze the failure mechanism of the primary support; then, illustrate the necessity of using antifreeze measures on the investigation and analysis of the temperature field distribution in seasonal frozen soil tunnel; mainly, the anti freezing effect of winter-proofing door is analyzed, results show that the temperature turned into positive temperature from the tunnel portal of 50 m; finally,from the use of low temperature resistance of sprayed concrete technology, the winter-proofing door and air curtain, grouting for surrounding rock, heat with stovepipe and electricity, measures of initial supporting are summarized.