红黏土裂隙湿化自愈行为及强度影响机制

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中文摘要：许多黏性土在干缩开裂后受湿化作用会呈现裂隙自愈现象.为探究红黏土裂隙自愈行为及其对土体强度特性的影响机制,基于摄影识别与数字图像相关技术,分析湿化过程中红黏土试样顶面裂隙自愈与应变演化规律;并开展单轴拉伸试验与直剪试验,获取不同条件下红黏土的抗拉强度、抗剪强度及指标恢复率.最后采用扫描电镜观察裂隙自愈前后试样的微观形貌,阐明红黏土裂隙自愈及强度影响机制.结果表明:红黏土在湿化条件下表现出裂隙自愈行为,自愈过程中压应变区域不断向裂隙靠近,裂隙率快速减小并趋于稳定,裂隙自愈率可达90％以上;随饱水湿化时间增加,含裂隙红黏土的抗拉强度小幅提升,此时土表裂隙痕迹几乎消失;湿化条件下土颗粒膨胀程度有限,裂隙宽度越大其愈合难度越高,抗拉强度恢复程度也越低;裂隙深度增加后裂隙自愈率小幅提升,抗拉强度与黏聚力的恢复率增加,内摩擦角恢复率先减小后稳定;裂隙自愈主要源于土颗粒膨胀变形后引起裂隙两侧壁相互黏结,以及土颗粒崩解剥落后对裂隙的填充效应;由于细小颗粒与水混合后可能吸附在裂隙内形成假愈合现象,且土颗粒膨胀崩解将影响土体强度,故尽管表观上裂隙愈合程度良好,但抗拉强度与抗剪强度指标仅小幅恢复.

外文标题：Mechanisms Behind Wetting Self-healing Behavior and Its Influence on the Strength of Lateritic Soil

外文摘要：The phenomenon of crack self-healing can be found in many clayey soils under wetting conditions.This study aimed to explore the self-healing behavior as well as the mechanism behind its influence on the strength characteristics of lateritic soil.The crack self-healing and strain evolution on the top surface of lateritic soil specimens in the wetting process were analyzed based on photographic identification and digital image correlation techniques.Afterward,the tensile strengths shear strengths and the recovery rates of their parameters were examined by uniaxial tensile tests and direct shear tests under different conditions.Finally,the microscopic morphology of the specimens before and after crack self-healing was observed by scanning electron microscopy,and thus the mechanisms underlying the self-healing of cracks and its influence on soil strength were revealed.The results demonstrate that lateritic soil exhibits crack self-healing behavior during wetting.The compressive strain area keeps approaching the crack in the self-healing process,and the crack rate of lateritic soil decreases rapidly and gradually stabilizes,showing a crack self-healing rate above 90％.The tensile strength of lateritic soil increases slightly with an increase in wetting duration.At this time,the crack marks on the soil surface almost disappear.The swelling capacity of soil particles under wetting conditions is limited,and the larger the crack width,the higher the difficulty of crack self-healing.Thus,the recovery rate of the tensile strength is lower.When the crack depth increases,the crack self-healing rate slightly increases,the recovery rates of the tensile strength and cohesion increase,and the recovery rate of the internal friction angle decreases first and then stabilizes.The self-healing behavior of the cracks mainly originates from the mutual bonding of soil particles on both walls of the cracks after swelling deformation and the filling effect of soil particles on cracks after disintegration and peeling off.Fine soil particles may be absorbed in the cracks after mixing with water to show a pseudo-healing phenomenon,and the strength of the soil may be affected by particle swelling and disintegration.For this reason,only a small recovery of tensile strength and shear strength parameters is observed although the crack heals well from the appearance.

外文关键词：

subgrade engineeringlateritic soilmicroscopic mechanismcrack self-healingstrength properties

作者：

高乾丰、吴昕阳、曾铃、余慧聪、余涵

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作者单位：

长沙理工大学特殊环境道路工程湖南省重点实验室,湖南长沙 410114

长沙理工大学交通运输工程学院,湖南长沙 410114

长沙理工大学土木工程学院,湖南长沙 410114

关键词：

路基工程红黏土微观机制裂隙自愈强度特性

基金：

国家自然科学基金项目国家自然科学基金项目湖南省自然科学基金项目长沙理工大学特殊环境道路工程湖南省重点实验室开放基金资助项目长沙理工大学研究生"实践创新与创业能力提升计划"项目湖南省研究生科研创新项目

项目编号：

52378439520080412021JJ40576kfj220502CLSJCX23013CX20230874

出版年：

2024

DOI：

10.19721/j.cnki.1001-7372.2024.06.013

中国公路学报

中国公路学会

中国公路学报

CSTPCD北大核心

影响因子：1.607

ISSN：1001-7372

年,卷(期)：2024.37(6)

参考文献量18