冻融循环下非饱和膨胀土一维土柱模型试验研究

This paper uses a one-dimensional soil column model to carry out freeze-thaw cycle tests on unsaturated expansive soils, and analyzes the changes in temperature and humidity, earth pressure, pore water pressure and vertical displacement at different depths during the freeze-thaw cycle. The test results show that: (1) During the freezing process, the soil temperature can be divided into five different stages: supercooling, jumping, constant, descending, and stable, and there are obvious jumping points and freezing points. There is no obvious overheating or sudden change during the heating process. (2) During the freezing process, the unfrozen water content gradually decreases with the decrease of temperature. After the freezing point of the soil, the unfrozen water content decreases faster, and there is always unfrozen water throughout the freezing and thawing process. There is a hysteresis phenomenon in the changes of soil temperature and unfrozen water content at different depths throughout the freeze-thaw process. (3) Changes in the temperature field and moisture field will cause changes in the stress state of the soil, which will lead to changes in earth pressure and pore water pressure. Among them, the first freeze-thaw has the greatest influence on these two pressures, and the changes gradually become slow with the increase of the number of freeze-thaw cycles. (4) During the freezing and thawing process, the vertical displacement of the soil will change in a wave shape. The transformation of the water phase has the greatest influence on the displacement, and the thermal expansion and contraction of soil particles and mineral components have the least influence.