Abstract
In this article, changes of pore water pressures (PWP) in silty clay subjected to freezing and thawing were measured under an open-system condition. A total of five soil samples were tested, with water contents of 10.70%, 18.28%, 23.98%, 31.00%, and 37.65%, respectively. Each experienced a first-step freezing stage, a thawing stage, and a second-step freezing stage. The results showed that changes in PWP depended on the water content, soil type, salinity, ice content, air, pressure, temperature, and others. The PWP minimum with initial water content has a “w-shaped double-valley” characteristic, which described two PWP minima existing in two optimum water contents as initial water content increased. An influence-factor analysis of PWP was proposed and gave a reasonable interpretation on the “w-shaped double-valley” characteristic of PWP. In addition, the tensiometer method to measure PWP in frozen soil was further discussed with regard to its advantages and disadvantages.
Highlights
Construction and operation in cold regions may encounter many environmental and engineering problems, such as permafrost degradation, frost heaving, icing, thaw settlement, thermokarst, and infrastructure failure
With the development of our country’s economy and implementation of Western development strategy, increasing projects are built in cold regions, including railway, highway, power transmission line, and petroleum pipeline. erefore, increasing research work begins to focus on the deformation process of frozen soil involving construction of these projects
(2) Samples with different water contents differed greatly in water volumes absorbed into the samples, and the water volumes absorbed into samples decreased as the initial water content increased
Summary
Construction and operation in cold regions may encounter many environmental and engineering problems, such as permafrost degradation, frost heaving, icing, thaw settlement, thermokarst, and infrastructure failure. Erefore, increasing research work begins to focus on the deformation process of frozen soil involving construction of these projects. Frost heave and thaw settlement are two uppermost hazards generally causing significant damages during engineering construction and operation, and accurate prediction of the deformation process is an important issue that needs to be urgently solved. Water migration and ice segregation as two essential issues of the frost heave and thaw settlement problem have always been of interest to researchers [1, 2]. PWP measurement in freezing soil has been an essential and key research work for further exploring the mechanisms of water migration and ice segregation [11]
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