Wang Jiacheng, Xu Xiaozu, Zhang Lixin, Wang Yujie
The controlled freezing tests were conducted on Neimong clay in open system under twodifferent temperatures and pressures, respectively. Results show that the boundary tempera-tures control the freezing rate, temperature gradient, direction and rate and amount of watermigration. Thus it influences the rate of phase change of soil water,location and amount ofice foimation. The direction and magnitude of pressure influence the direction and amount ofwater migration and temperature of phase change. Thus it influences the degree of ice foma-tion. If the temperature boundary condition is the same,the cryogenic structure isunderdeveloped in layers and thickness of segregative ice,because the overburden pressureresults in densification of soil body,hysteresis of water intake flow, freezing point depressionand decreasing of amount of water intake flow.If the overburden pressure is the same,themicfo-layered and thin-layered ice strips are developed better in the soll column with the temperature decreashg linearly at cold end than with constant temperature, because thetemperature gradient is increasing with time in the fonner and decreasing in the latter. The in-jection pressure promotes the development of cryogenic structure by increasing the amount ofwater intake flow. Phase change of water results in frost heaving of freezing soll. The two heatboundary conditions induce the process of fros theaving as power and linear function of time,respectively.The two pressures induce frostheaving decreasing and increasing respectively. The concept of suspend pressure only has relative meaning because it depends on the heatboundary condition.
