With the increase of construction in cold regions, many engineering problems involving frozen rock occur. According to the theory of heat and mass transfer for porous media,a numerical model for the coupled problem of hydro-thermal is established by considering heat and mass transfer and phase change for rock mass at low temperature. The influences of fluid transfer on the heat conduction and the temperature gradient on the seepage is considered in the model. The involved parameters are determined by the related equations are given. Then on the background of large scale rock engineering, and by adopting the finite element method, the numerical simulation is done to study the range of frost-thaw of surrounding rock and the effects of insulation material in cold regions, which analyze the influence of tunnel depth and surrounding rock class on the range of frost-thaw, the variation law of the frost-thaw area of different insulation material and the relationship between the frost-thaw area and the thickness of insulation material. The results can give some references for design and construction of tunnel in cold region.
Bonacina et al. (1973) presented a numerical solution in order to solve heat conductive problems with phase change. Comini et al. (1974) investigated nonlinear heat conduction problems with special reference to phase change by finite element methods. He et al. (1996) analyzed and preliminarily predicted the frozen–thawing situation in the surrounding rock of DabanShan tunnel. Lai et al. (1998) made nonlinear analyses for the coupled problem of temperature, seepage and stress fields in cold regions tunnel. He et al. (1999) studied the frozen–thawing situation in the rock surrounding the tunnels in cold regions by a combined convection–conduction model of turbulent airflow in the tunnels and temperature fields in the rock surrounding the tunnels. Many researchers have done different study and mainly focus on the water and heat migration (Miller, 1972; Taleda et al., 1997; Konrad et al., 1993). several hydro-thermal coupled numerical models have been developed and the hydrothermal coupled problem of rock engineering in cold region is suggested (Harlan, 1973; Sheppard et al., 1978; Taylor et al.,1978; Fukuda, 1982). In the existing model, only the effect of heat carried by water migration on temperature field is considered in soil or rock. While for the more important problems such as effect of water migration on thermophysical parameters, latent heat and segregation potential caused by temperature gradient haven't been considered. (Lei et al., 1998; Zhang et al., 2004; Wang et al., 2004). According to the theory of heat and mass transfer for porous media, a numerical models for the coupled problem of hydro-thermal is established by considering heat and mass transfer and phase change for rock at low temperature.