ABSTRACT
Taking a subway tunnel connecting passage in a water-rich gravel stratum as the research background, indoor strength tests were used to determine the mixing ratio of similar materials of gravel. According to the similarity criterion of freezing temperature field, moisture field, and stress field, a large-scale model test box with functions of loading, refrigeration, and monitoring was established to measure the temperature field, frost heave, and thaw settlement in real-time during the freezing process. The model test showed that when the soil temperature was above zero, the temperature drop gradient is greater. The soil around the freezing pipe became negative after an average of 150 minutes of freezing.The temperature drop rate decreased as the freezing process progressed. When the freezing rate was large, the drop rate of soil temperature was greater. During the frost heave stage, the displacement of the frozen wall and the ground surface increased gradually. The displacement of the frozen wall was greater than the displacement of the ground surface.The initial soil displacement in the thawing stage changed little, but with the continuous increase in soil temperature, the change in displacement increases. When the soil temperature reached the same as room temperature, the thawing displacement of the soil also tended to be stable. During the process of frost heave and thaw settlement, the displacement change of the frozen wall was larger than that of the ground surface.
