Freeze-thaw cycle phenomenon of soils can remarkably change the physical properties and microstructure of soil, thus influencing the service performance of engineering facilities significantly in permafrost regions. 

Therefore, it can be seen that the variations on physical properties and microstructures of soils are essential to explore the freeze-thaw mechanisms. 

Recently, scientists from Northwest Institute of Eco-Environment and Resources (NIEER) of the Chinese Academy of Sciences conducted some experiments on freeze-thaw test of Qinghai-Tibet Plateau silty clay and performed cryo-scanning electron microscope (cryo-SEM) observing after freeze-thaw test to monitor the changes of temperature, pore water pressure and displacement. 

The results showed that the change of pore water pressure was closely related to soil particles rearrange, particle size redistributing, and then developed a new arranging tendency of soil pores during freeze-thaw cycles. 

Besides, scientists also quantified cryo-SEM images by Image-pro Plus (IPP) software in this study, and the study result reflected that the change of pore water pressure had a certain correlation with structural parameters under freeze-thaw cycles. 

These findings substantially contribute to understand the freeze-thaw mechanism and assist in upscale the microscale physical characteristic of frozen soils. 

This research has been published on the Transportation Soil Engineering in Cold Regions in an article entitled “Experimental Study on Pore Water Pressure and Microstructures of Silty Clay Under Freeze-Thaw Cycles”. 

Contact: 

YANG Chengsong 

ychsong@lzb.ac.cn 

State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.