Experimental study on the unfrozen water content and the freezing temperature during freezing and thawing processes
LU Jianguo1，2，ZHANG Mingyi1，2，ZHANG Xiyin1，2，YAN Zhongrui1，2
(1. State Key Laboratory of Frozen Soil Engineering，Northwest Institute of Eco-environment and Resources，Chinese Academy of Sciences，Lanzhou，Gansu 730000，China；2. University of Chinese Academy of Sciences，Beijing 100049，China)
Abstract：The unfrozen water content is a key factor controlling the moisture migration and causing the frost heave or thaw settlement during freezing and thawing processes. The freezing temperature is an important index to judge whether the soils are in a frozen state or not. The characteristics of the unfrozen water content and the freezing temperature and their relationships with initial water content during the freezing and thawing processes of the silty clay from Qinghai—Tibet Plateau were analyzed based on the frequency domain reflectometry(FDR) technique. The results show that for the soil with the higher initial water content，there are distinct super-cooling phenomenon and abrupt change of temperature and unfrozen water content in the freezing process. But for the soil with the lower initial water content，the phenomenon is not obvious. The soil with the larger initial water content is frozen earlier than the soil with the smaller initial water content and is more sensitive to the temperature jump. The lag effect of the unfrozen water content between the freezing and thawing processes is affected by the initial water content. The lag degree of unfrozen water content is mainly in the phase change zone. The peak value of the lag unfrozen water content decreases with the reduction of the initial water content. The initial water content has little influence on the freezing temperature of soil when the water content is equal or greater than the liquid limit. The freezing temperature of soil decreases with the reduction of the water content if the initial water content is less than the liquid limit.
路建国1，2，张明义1，2，张熙胤1，2，晏忠瑞1，2. 冻融过程中未冻水含量及冻结温度的试验研究[J]. 岩石力学与工程学报, 2017, 36(7): 1803-1812.
LU Jianguo1，2，ZHANG Mingyi1，2，ZHANG Xiyin1，2，YAN Zhongrui1，2. Experimental study on the unfrozen water content and the freezing temperature during freezing and thawing processes. , 2017, 36(7): 1803-1812.
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2017, Vol. 36 
