The impact of environmental temperature change on the interior temperature of quasi-sandstone in cold region: Experiment and numerical simulation

The purpose of this study was to simulate the internal temperature (T) change behavior of rocks as environmental T passes through the freezing point, 0 °C, in cold region. These data are important to determine the overall heat transfer rules of rock bodies during freeze-thaw cycles. First, a series of indoor experiments were carried out to measure the interior T changes of quasi-sandstone specimens when environmental Ts were cycled from 20 °C to −20 °C. The results of these tests show that interior T curves exhibit a typical 'three-period' change during the freezing or thawing process, in particular incorporating a clear slowdown period around environmental T that range between 0 °C and −4 °C. Second, using these data, we established an apparent heat capacity model (AHCM) based on heat transfer theory. This model was then embedded into the COMSOL program to simulate change rules of the interior T field. Moreover, latent heat linked to phase change was also considered based on three common correlation formulas that relate unfrozen water content and phase T. These comparisons indicate that simulated results based on a previously proposed empirical expression seemed to fit best with experimental results. Finally, five groups of symmetric and asymmetric environmental Ts were selected respectively in order to discuss the influence of these environmental variables on the interior T changes of rock samples. We therefore generalize that these three parameters are the key factors influencing the duration of the freezing period.