(1. Institute of Geotechnical Engineering，Xi?an University of Technology，Xi?an，Shaanxi 710048，China；2. Xi?an Research Institute，CCTEG，Xi?an，Shaanxi 710077，China；3. State Key Laboratory of Frozen Soil Engineering，Northwest Institute of Eco-environment and Resources，Chinese Academy of Sciences，Lanzhou，Gansu 730000，China；4. School of Civil Engineering，Lanzhou Jiaotong University，Lanzhou，Gansu 730070，China)
Abstract：In the freezing-thawing environment，temperature is one of the key factors influencing the physical and mechanical characteristics of rock. However，the thermal transfer and temperature change in rock in the freezing-thawing test have not been fully understood. The experimental and numerical methods were therefore applied to analyse the process of heat balance. Three kinds of rocks were studied in the freezing and thawing tests with the temperature being monitored. The process of central temperature change contains in three stages such as the precooling stage，the phase transition stage of moisture and the cryogenic stage during freezing，and the process during thawing includes the preheating stage，the phase transition stage of moisture and the deep heating stage. The phase transition stage is special and significant in the freezing and thawing test. The temperature of phase transition is between 0 ℃ and －1 ℃ for all the specimens. As the temperature range increases，the durations of each stage in the freezing and thawing processes are different. The total duration decreases gradually in the freezing process，but decreases first and then increases in the thawing process. The processes of freezing and thawing for the saturated rock were analyzed with the software of Comsol Multiphysics considering the phase transition of moisture. The results of numerical simulation match well with the test results. According to the numerical simulation results，the characteristic differences of the freezing and thawing process are mainly in the phase transition stage and the porosity of rock influences the stage greatly. The residual of heat potential results in the differences between the symmetrical and unsymmetrical temperature range in the freezing and thawing process.
2016, Vol. 35 
