Experimental study on the effect of cyclic freezing-thawing on mechanical properties of silty clay with different degrees of compaction
HU Tianfei1，LIU Jiankun1，FANG Jianhong2，CHANG Dan1，LIU Dawei1
(1. School of Civil Engineering，Beijing Jiaotong University，Beijing 100044，China；2. Qinghai Transportation Research Institute，Xining，Qinghai 810008，China)
Abstract：The cyclic freezing-thawing is one of the main factors causing the performance deterioration of the subgrade filling material in cold regions. In order to identify the effect of the original compaction degree on the variation of mechanical properties of silty clay in Qinghai—Tibet Plateau，a series of triaxial tests were performed with different degrees of compaction under freezing-thawing cycles. The results show that the levels of original compaction degree affect considerably the freezing and thawing effect on soil mechanical properties. The forms of stress-strain relation of samples with different degrees of compaction are similar，changing from the strain softening to hardening after several freezing-thawing cycles. The water migration inside samples under the closed condition during the freezing and thawing lead to the partition of zones with the moisture content increase and decrease respectively. The sample with the lower compaction degree has a bigger zone with the moisture content increasing. The effect of freeze-thaw cycles on the failure strength decrease for the samples with high compaction degree，and increase for those with low compaction degree. The relationship between the shear strength and the moisture content can be expressed as a nonlinear function，and the redistribution of the moisture content inside the samples leads the change of overall shear strength. After the repeated cyclic freezing-thawing，the cohesion of samples with the high compaction degree decreases，while that with the low compaction degree increases. The internal angle of friction always increases after the redistribution of moisture content，and the lower compaction degree causes the higher increasing rate. Hence both the dry density and water redistribution affect the mechanical properties of samples，and their effects exist simultaneously during the freezing-thawing cycles. Which of these two factors played the leading role depends on the original compaction degree and the number of freezing-thawing cycles.
胡田飞1，刘建坤1，房建宏2，常 丹1，刘大伟1. 冻融循环下压实度对粉质黏土力学性质影响的试验研究[J]. 岩石力学与工程学报, 2017, 36(6): 1495-1503.
HU Tianfei1，LIU Jiankun1，FANG Jianhong2，CHANG Dan1，LIU Dawei1. Experimental study on the effect of cyclic freezing-thawing on mechanical properties of silty clay with different degrees of compaction. , 2017, 36(6): 1495-1503.
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2017, Vol. 36 
