Study On Calculation Method And Temperature Response Of Anti-freezing Fortification Length Of Tunnel Section Of Permafrost Tunnel

The permafrost tunnel often suffers the influence of frozen damage to make the tunnel cannot use normally because of the terrible weather of the permafrost region. In order to prevention and cure those frozen damages, combined with the frozen damage data of permafrost tunnel and Feng Huoshan tunnel, and with the help of the project of the longitudinal temperature field characteristics and research of segmental anti-freezing of high altitude tunnel in frozen earth. The literature researches method can be used to analyze the frost damage characteristics, frost damage reason and the place of frost damage. Then the formula of the anti-freezing fortification length can be got based on the heat transfer theory and method of mathematical physics. And the correctness of result from the formula can be tested by the numerical simulation method and the temperature data of Feng Huoshan tunnel to solve the difficulties and shortage of the anti-freezing measures. The results got from this paper can be saw as the following:(1) The frozen damage in the area from the tunnel portal to the specific length of tunnel body can be really serious by the result from frozen damage characteristic of twenty-five tunnels. The primary cause is the chaos temperature in this area. So this area should be considered in the term of the aspect of anti-freezing fortification of the tunnel in frozen earth.(2) The formula about the transverse direction temperature field regularity and the vertical temperature field regularity can be obtained by using the heat transfer theory and method of mathematical physics. Then the influences on the temperature field distribution characteristic along the tunnel direction and transverse direction be analyzed under condition of the different tunnel depth, different tunnel air velocity, with or without insulating layer to get the tunnel anti-freezing fortification length.(3) The unstable temperature length can be got from the finite element software ADINA to build the three-dimensional analysis model with consideration of different factors based on the tunnel of Feng Huoshan.(4) The temperature field distribution characteristic of Feng Huoshan tunnel along the tunnel direction and transverse direction can be obtained from the temperature monitoring data to test the rationality of the result from the theory and the numerical simulation method. So the suggestion can be got for the anti-freezing fortification length.