Research on variability of freezing-thawing cycle on basic physical and mechanics properties of clay minerals
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摘要: 冻土工程破坏主要的原因之一是冻融循环作用。通过对高岭土(主要黏土矿物为高岭石)、膨润土(主要黏土矿物为蒙脱石)在反复冻融作用下的物理性质试验及球模仪试验，研究高岭土及膨润土在冻融循环作用下的物理力学性质变化，并由此推定不同黏土矿物含量土在冻融循环作用下物理力学的变化规律。结果表明：(1)前10次冻融循环对高岭土及膨润土的物理力学性能影响很大，冻融10次后，随冻融次数的增加，高岭土的密度下降，孔隙比增加，膨润土的密度增加，孔隙比减小；(2)冻融过程中物理性质的变化不仅与土样的种类有关，也与土样的矿物成分有关；(3)高岭土的长期强度C24远高于膨润土，但是冻融过程中高岭土的力学性能变化较大，而膨润土相对比较稳定。Abstract: The effect of freezing-thawing cycle is one of the main causes for destruction of frozen soil engineering. Under the effect of freezing-thawing cycles, tremendous changes will occur in the engineering properties of soil, which resulting in the deformation and failure of engineering in cold regions. By testing the physical properties and conducting spherical template indenter tests of kaolin (with the main clay minerals of kaolinite) and bentonite (with the main clay minerals of smectite). After repeated freezing and thawing tests, the changes in physical-mechanical properties of kaolin and bentonite under the effect of freezing-thawing cycle are examined, and the change rule of the physical-mechanics properties of the soil with different clay minerals under the effect of freezing-thawing cycle can be speculated. The results show that (1) the first 10 times of the freezing-thawing cycle have important effect on the physical and mechanical properties of kaolin and bentonite. After 10 times of freezing and thawing, with the increasing number of freezing and thawing time, the density of kaolin decreases and the pore ratio increases, and the density of bentonite increases and the pore ratio decrease; (2) changes in soil physical properties are not only related to the types of the soil samples, but also the essential effect of the mineral compositions of the soil; (3) kaolin’s long-term strength (C24) is much higher than that of the bentonite (C24). However, in the process of freezing and thawing, the change in the kaolin’s mechanic performance is larger, and the bentonite’s mechanic performance is relatively stable.
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Key words:
- freeze-thaw cycle /
- clay mineral /
- physico-mechanical properties /
- long-term strength
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