Numerical simulation of frost heaving damage of earth-rock dam berms in cold regions with thermo-hydro-mechanical coupling

Abstract

In order to investigate the freezing damage problem of berms of earth-rock dams in cold regions, an earth-rock dam in a cold region was selected as the research object in this study. A finite element model, considering the effect of thermo-hydro-mechanical coupling, has been developed to solve the problem by combining the characteristics of the earth-rock dam. The whole process of freezing damage of berms under the influence of the reservoir level and the water migration of the dam filling was investigated, and the laws in temperature, humidity and displacement of earth-rock dams were analyzed. The calculated displacement field was then compared with the measured frozen deformation data to validate the results of the finite element simulation. The results showed that the freezing influence range of the dam slope was about 2 m, the range of temperature influence on the dam slope mainly depended on the depth of freezing, and the temperature change in the shallow range (0–2 m) of the dam slope was influenced by the outside air temperature. Also, the internal temperature of the dam body was small relative to the shallow dam slope, and there was a certain hysteresis. In addition, the effect of negative temperature was such that the shallow pore water phase of the dam slope turned into ice, manifesting macroscopically as a reduction in unfrozen water content. Water phase change, water migration from the dam filling to the dam slope, and the movement of the ice peak towards the dam body were found to be the main causes of berm freezing and expansion damage. The calculated amount expansion (due to freezing) of the dam slope was found to be in the range of 20–30 cm with a maximum value of 36 cm, which was consistent with the measured results. It was also found that the freezing and expansion damage of the berm is mainly caused by the joint action of freezing and expansion of the soil and rock mixture such as gravel bedding and dam filling, as well as the ice thrust force. It is expected that the results of this research can provide a basis for the design of berms of earth-rock dams in cold regions.