1. College of Civil Engineering and Architecture, Guilin University of Technology, Guilin 541004, China 2. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China 3. Key Laboratory of Bridge and Tunnel Health Monitoring and Safety Assessment Technology of Gansu Province, Gansu Provincial Transportation Research Institute Co. Ltd, Lanzhou 730030, China 4. School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing 100083, China
The unfrozen water mass fraction is the key parameter to evaluate the stability of the soil during the freezing process of saline and coastal areas. The main influencing factors are temperature and salt mass fraction. The differential form of matric suction of frozen soil was obtained by the freezing characteristic curve of salt-free soil, based on the generalized Clapeyron equation considering solute effect, and the Books-Corey model with residual water mass fraction. A theoretical model of soil freezing characteristic curve were derived for frozen soil under arbitrary salt mass fraction and temperature conditions. The freezing test was carried out, and the freezing characteristic curves of silty clay and silt under different water mass fraction and salt mass fraction were obtained by nuclear magnetic resonance. The results show that the mass fraction of unfrozen water decreases exponentially with the reduction of temperature. The unfrozen water mass fraction increases linearly with the increasement of initial solution concentration at the same temperature. The freezing characteristic curves of salt-free soil with different initial water mass fraction are consistent. The silt reaches the residual state more easily than the silty clay. It is verified that the model can predict the freezing characteristic curve of saline soil reasonably by comparing the theoretical model with the test data.
Xiang-chuan MENG,Jia-zuo ZHOU,Chang-fu WEI,Pan CHEN,Kun ZHANG,Zheng-yan SHEN. Freezing characteristic curve model of saline soil based on generalized Clapeyron equation. Journal of ZheJiang University (Engineering Science), 2020, 54(12): 2377-2385.
Fig.3Calculation principle of unfrozen water mass fraction
Fig.4Variation curve of unfrozen water mass fraction with temperature in soils with different salt mass fraction
Fig.5Comparison of residual water mass fraction in model
Fig.6Variation curve of unfrozen water mass fraction with temperature in clay with different moisture mass fraction
土样
w0 /%
a
N
wr /%
θs /°C
饱和粉土
26.0
0.016
1.1790
2.0
?0.10
非饱和粉土
15.0
0.022
0.7011
1.9
?0.08
非饱和粉质黏土
15.0
0.092
0.4000
1.0
?0.35
Tab.2Values of sample fitting model parameters
Fig.7Curve of unfrozen water mass fraction of silt at different temperatures with initial salt mass fraction
Fig.8Curve of unfrozen water mass fraction of silt at different temperatures with salt mass fraction
Fig.9Variation curve of unfrozen water mass fraction with temperature in Morin clay with different salt mass fraction
Fig.10Variation curve of unfrozen water mass fraction of unsalted soil with temperature
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