Effect of freeze-thaw cycles on uniaxial mechanical properties of cohesive coarse-grained soils
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Freeze-thaw cycles are closely related to the slope instability in high-altitude mountain regions. In this study, cohesive coarse-grained soils were collected from a high-altitude slope in the Qinghai-Tibet Plateau to study the effect of cyclic freeze-thaw on their uniaxial mechanical properties. The soil specimens were remolded with three dry densities and three moisture contents. Then, after performing a series of freeze-thaw tests in a closed system without water supply, the soil specimens were subjected to a uniaxial compression test. The results showed that the stress-strain curves of the tested soils mainly performed as strain-softening. The softening feature intensified with the increasing dry density but weakened with an increase in freeze-thaw cycles and moisture content. The uniaxial compressive strength, resilient modulus, residual strength and softening modulus decreased considerably with the increase of freeze-thaw cycles. After more than nine freeze-thaw cycles, these four parameters tended to be stable. These parameters increased with the increase of dry density and decreased with the increasing moisture content, except for the residual strength which did not exhibit any clear variation with an increase in moisture content. The residual strength, however, generally increased with an increase in dry density. The soil structural damage caused by frozen water expansion during the freeze-thaw is the major cause for the changes in mechanical behaviors of cohesive coarse-grained soils. With results in this study, the deterioration effect of freeze-thaw cycles on the mechanical properties of soils should be considered during the slope stability analysis in high-altitude mountain regions.
KeywordsFreeze thaw cycles Residual strength Resilient modulus Softening modulus Uniaxial compressive strength Slope stability
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The authors wish to express their gratitude to three anonymous reviewers for their constructive comments and suggestions. This study was supported by the National Key R&D Program of China (Grant No. 2018YFC1505001), the Key Scientific Research Project of China Gold Group (Grant No. 2016ZGHJ/XZHTL-YQSC-26), the funding from the Department of Transportation of Gansu Province (Grant No. 2017–008), the Fundamental Research Funds for the Central Universities, CHD (Grant No. 300102268716). The authors would like to thank Prof. ZHANG Shujuan and Mr. CHEN Tao for their kind help during the laboratory tests.
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