干湿循环条件下不同初始干密度土体的力学特性

发布时间：2018-06-15 03:53

本文选题：干湿循环 + 干密度　；参考：《水利学报》2014年03期

【摘要】：利用应力-应变控制式三轴剪切渗透试验仪,测试了大连地区典型粉质黏土试样干湿循环前后的力学特性。通过对干湿循环前后试样固结不排水剪切试验的应力-应变关系、孔隙水压力和有效应力路径等试验结果的对比分析,探讨了干湿循环对不同初始干密度土体力学特性的影响,结果表明:土体对干湿循环的响应与土体的初始干密度有关。干湿循环使得初始干密度为1.61g/cm3的试样的应力-应变关系曲线由应变硬化转变为应变软化,孔隙水压力的发展由先增加后减小转变为孔压持续增长,循环前后有效应力路径的发展趋势发生了明显变化。初始干密度1.71g/cm3和1.76g/cm3试样干湿循环前后的应力-应变关系曲线形式未发生明显改变,干湿循环致使孔隙水压力的峰值所有增加,剪切初始阶段的有效应力路径位于未循环试样的左侧。干湿循环前后土体的电镜扫描(SEM)试验发现,干湿循环导致土骨架的结构性转变。干湿循环过程中试样内部结构调整和基质吸力的压密作用使得土体的力学特性发生了不可逆转的变化。
[Abstract]:The mechanical properties of typical silty clay samples in Dalian area before and after dry and wet cycling were measured by means of a stress-strain controlled triaxial shear permeation tester. By comparing and analyzing the stress-strain relationship, pore water pressure and effective stress path of undrained shear tests before and after dry and wet cycling, the effects of dry and wet cycles on the mechanical properties of soils with different initial dry densities are discussed. The results show that the response of soil to dry and wet circulation is related to the initial dry density of soil. Dry and wet cycles change the stress-strain relationship curve of samples with initial dry density of 1.61g/cm3 from strain hardening to strain softening, and the development of pore water pressure changes from first increasing and then decreasing to continuous increase of pore pressure. The development trend of effective stress path before and after cycle has changed obviously. The stress-strain curve of the initial dry density 1.71g/cm3 and 1.76g/cm3 samples before and after dry and wet cycling has not changed obviously, and the peak value of pore water pressure increases due to dry and wet cycles. The effective stress path at the initial stage of shear is located on the left side of the uncyclic specimen. Scanning electron microscope (SEM) tests before and after dry and wet cycles show that dry and wet cycles lead to structural transformation of soil skeleton. The internal structure adjustment and the compaction of the matrix suction make the mechanical properties of soil irreversibly change during the dry and wet cycle.
【作者单位】：大连理工大学岩土工程研究所;大连理工大学海岸和近海工程国家重点实验室;
【基金】：国家自然科学基金资助项目(51179023)
【分类号】：TU442

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