ABSTRACT
There are many cold region tunnels in China, Canada, Norway, Japan and Russia. In the northwest and northeast of China, because of the damage caused by frost and thaw action, some of the tunnels cannot be used for up to 8–9 months a year and transportation is negatively affected (Lai et al., 1999). So the research work on reasonable cold-proof measures is of great importance to prevent their linings from being destroyed by the frost heave or thaw settlement for the cold region tunnels (Huang et al., 1986; Johansen et al., 1988; Qiao et al., 2003). In Russia, the pipe-electric heaters heat the tunnels, and the new type and effective insulations preserve the heat of the cold region tunnels. In Norway, some of the drains in the tunnels are heated with the heated cables, some are fitted with double thermal insulation doors; and others have insulation installed. In Japan, the insulation materials are put on the lining surfaces of Shang Yu Huang tunnel at Hokkaido to prevent the local geothermal from giving out and to keep the temperatures on the lining surface from falling below the frozen temperature (Johansen et al., 1986; Okada et al., 1985; Sandegren, 1995; Zhang et al., 2002; Guan, 2003; Lai et al., 2005). In China, to keep the initial thermal situations of the surrounding rock from being broken and to prevent their linings from being destroyed, many useful methods, such as slurry injected, insulation material (such as polyphenyl plate, XPS plate), thermal insulating door, snowshed and drainage hole and so on, are proposed in cold region tunnels. Mie (1983) put forward a method for protecting tunnel from frost damage with the thermal insulation layer. Tang & Wang (2007) analyzed the effect of temperature control on a tunnel in permafrost, and the stability conditions related to the thawing depth and suitable for use during construction were established. According to the basal theories of heat transfer and seepage, considering the coupled effect of seepage field and temperature field, Zhang et al. (2007) studied the function of the insulation layer for treating water leakage in permafrost tunnels, three-dimensional nonlinear analysis was made either with or without the insulation layer, and the result showed that it is necessary for treating water leakage to fit 244the insulation layer between the two linings in Kunlun mountain tunnel. In order to research the actions of the thermal insulation material in the process of the re-frozen of permafrost Tunnel, the re-frozen analysis of Feng Huoshan tunnel with the thermal insulation material was made by Zhang et al. (2004). According to the observation in-situ temperature of Daban mountain tunnel in Qinghai province either with or without the insulation layer, Zhang (2000) suggested that the thermal insulating door and the snowshed were the useful method to prevent the tunnel from frost. Based on the field test of chosen material's performance of anti-freezing thermal protective 1ayer in Daban mountain tunnel and field contrast experiments, optimum combination and construction of anti-freezing thermal protective layer materials are determined by Chen & Zan (2003). After these field experiments, a design method for anti-freezing thermal protective layers in cold area tunnels was given by Chen (2004). Lai et al. (2003) studied the methods for controlling frost heave in cold region tunnels. Zhou (2003) studied the constructing technology of insulation layer, water-proof and drainage water in Kunlun mountain tunnel on Qinghai–Tibet railway.
