Research PaperExperimental study on the water-heat-vapor behavior in a freezing coarse-grained soil

- The frost susceptibility of coarse-grained soil considering “pot” effect is investigated.
- The influence of fines and initial water content on the moisture migration and frost susceptibility is studied.
- The effect of vapor transfer and external water supply on the frost heave of coarse-grained soil is evaluated.

A series of one-side freezing experiments of a coarse-grained soil with different contents of clayey loess were conducted in an open system with no-pressure water supply, to evaluate the influence of fines content and initial water content on the moisture migration and frost susceptibility of the coarse-grained soil, and to investigate the frost heave mechanism of coarse-grained soil under consideration of “pot” effect. The experimental results show that a thin ice layer appears in the cold end boundary by simulating the impervious cover, which is an important reason for the frost heave of coarse-grained soil. The frost susceptibility of the coarse-grained soil is influenced by fines content significantly, and the amount of frost heaving and frost heave ratio of soil samples increase linearly with the increase of fines content. The influence of external water on the frost susceptibility of the coarse-grained soil could not be neglected, and with the increase of fines content, the external water supply will increase. Meanwhile, with the increase of initial water content, the frost heave of coarse-grained soil increases. The start time of water intake is delayed, and it would be enlarged with the decreases of fines content and initial water content. Besides, it is also found that in the case of lower moisture content, the effect of vapor transfer on the frost heave of coarse-grained soil will become more obvious.