冻融循环下压实度对粉质黏土力学性质影响的试验研究

发布时间：2018-03-29 16:27

本文选题：土力学　切入点：粉质黏土　出处：《岩石力学与工程学报》2017年06期

【摘要】：冻融循环是冻土地区路基填料性能劣化的主要因素之一。以压实度和冻融循环次数为主要变量,对青藏高原粉质黏土力学性质的变化规律进行三轴试验研究。试验结果表明:初始压实度对粉质黏土力学性质的冻融效应具有显著影响。不同压实度试样的应力应变曲线形式随冻融次数的增加趋于接近,并由应变软化型向硬化型过渡。封闭系统中试样的水分迁移会引起含水率的增减分区分布,低压实度有利于增大水分迁移量和含水率增高区的分布范围。冻融过程对高压实试样的破坏强度以降低为主,对低压实度试样则相反。在最优含水率附近,土体抗剪强度随含水率呈非线性变化规律,因此试样内部水分重分布也可能会导致强度的改变,且其作用效果受压实度影响具有不确定性,压实度较高时会导致试样黏聚力减小,压实度较低时则相反;不同压实度下内摩擦角均呈现增大的趋势,且压实度越低,变化幅度越大。冻融过程中,土体干密度和含水率变化对力学性质的影响是同时存在的,由于初始压实度和冻融次数的不同,对强度变化起主导作用的因素也不同。水分重分布是不同压实度土体力学性质冻融循环效应的整体趋势和具体过程呈现多样化的原因之一。
[Abstract]:Freeze-thaw cycle is one of the main factors for the deterioration of the performance of subgrade fillers in permafrost regions. The compaction degree and the number of freeze-thaw cycles are the main variables. The variation of mechanical properties of silty clay in Qinghai-Xizang Plateau is studied by triaxial test. The experimental results show that initial compaction has a significant effect on the freeze-thaw effect of silty clay. With the increase of freeze-thaw times, the form of strain curve tends to be close. And the transition from strain softening type to hardening type. The moisture migration of the sample in the closed system will cause the increase or decrease of the distribution of water content. Low compaction is beneficial to increase the distribution range of water migration and water content increase. The failure strength of freeze-thaw high pressure specimen is mainly decreased, while the low compaction sample is opposite, near the optimal moisture content, the failure strength of freeze-thawing process is mainly reduced to that of high pressure solid sample, while the low compaction degree is opposite. The shear strength of the soil changes with the moisture content, so the distribution of moisture in the sample may cause the change of the strength, and the influence of the compaction on the shear strength is uncertain. When the compaction degree is high, the cohesion of the specimen will decrease, but when the compaction degree is low, the internal friction angle will increase, and the lower the compaction degree, the greater the change. The influence of soil dry density and moisture content on mechanical properties exists simultaneously, because of the difference of initial compaction and freeze-thaw times. The distribution of water redistribution is one of the reasons why the freeze-thaw cycle effect of different compaction degree soil mass is varied.
【作者单位】：北京交通大学土木建筑工程学院;青海省交通科学研究院;
【基金】：国家自然科学基金资助项目(51378057,41371081) 国家重点基础研究发展计划(973)项目(2012CB026104)~~
【分类号】：TU41

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