干湿循环作用下红黏土收缩特征研究

发布时间：2018-01-28 17:04

本文关键词： 红黏土干湿循环收缩曲线收缩变形含水率　出处：《冰川冻土》2016年04期 　论文类型：期刊论文

【摘要】：以贵州某高速公路沿线红黏土为研究对象,开展了干湿循环作用后红黏土的收缩特性试验研究,探讨了干湿循环次数和初始含水率对红黏土收缩性状的影响.试验结果表明:同一循环次数内,各试样的环向收缩率在6~8 h时达到稳定,而轴向线缩率则需更长的稳定时间;随着初始含水率增加,各试样的初始轴向线缩率减小,而初始环向收缩率增加;28%含水率试样具有相近的最终轴向变形和环向变形量,而34%含水率的试样环向变形量高于轴向变形量;初始含水率变化不大,但体缩率的变化率却明显不同,说明干湿循环过程使得土体内部结构变得不稳定,但颗粒间相互作用的本质未发生明显变化;干湿循环作用对重塑红黏土最优含水率位置的基本无影响,这说明其未能改变黏土集聚体内对结合水的最大吸附能力.通过压汞试验得到了不同干湿循环作用后试样的孔隙分布情况,随着干湿循环次数的增加小孔径尺寸和分布密度改变较小,而大孔径尺寸减小,分布密度也在减小.干湿循环作用对聚集体内孔径的影响大于对微聚体内孔隙影响,与所测得的宏观收缩规律相吻合.
[Abstract]:Taking red clay along a highway in Guizhou as the research object, the shrinkage characteristics of red clay after dry and wet circulation were studied. The effects of dry and wet cycle times and initial moisture content on shrinkage behavior of red clay were discussed. The experimental results showed that the circumferential shrinkage of each sample reached stability at 6 ~ 8 h in the same cycle number. The axial linear shrinkage takes a longer time to stabilize. With the increase of initial moisture content, the initial axial shrinkage decreases and the initial circumferential shrinkage increases. The final axial deformation and toroidal deformation of 28% moisture content sample are similar, while the circumferential deformation amount of 34% moisture content sample is higher than that of axial deformation. The change rate of initial moisture content is small, but the change rate of volume shrinkage rate is obviously different, which indicates that the internal structure of soil becomes unstable during dry and wet circulation process, but the essence of interaction between particles does not change obviously. The effect of dry-wet cycle has no effect on the optimal moisture content of remolded red clay. This shows that it can not change the maximum adsorption capacity of clay agglomeration to binding water, and the pore distribution of samples after different dry and wet cycles is obtained by mercury injection test. With the increase of dry-wet cycles, the small pore size and distribution density change slightly, while the large pore size decreases. The distribution density is also decreasing. The effect of dry and wet circulation on pore size in aggregates is greater than that on pore size in micropolymer, which is consistent with the measured macro shrinkage.
【作者单位】：常州工学院土木建筑工程学院;常州市建筑科学研究院股份有限公司;湖南科技大学土木工程学院;
【基金】：国家自然科学基金项目(41302226) 江苏省自然科学基金项目(BK20131141) 常州工学院校级科研项目(YN1501) 岩土工程稳定控制与健康监测湖南省重点实验室开放基金项目(E21620)资助
【分类号】：U412.22
【正文快照】： 0引言红黏土是一种典型的特殊土,在我国云贵高原、两湖两广等地区有大面积出露,其形成具有特定的气候环境,一般都在炎热多雨地区.已有研究表明,红黏土浸水后膨胀性轻微,失水后收缩明显,即具有低膨胀性和高收缩性的特征.而土体收缩导致的裂缝将成为水分入侵与蒸发的良好通道,也

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