Effects of microstructure on desiccation cracking of a compacted soil
Effects of microstructure on desiccation cracking of a compacted soil
复制标题
微结构对压实土干燥开裂的影响
DOI：
10.1016/j.enggeo.2019.105418
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发表时间：
2020
影响因子：
7.4
通讯作者：
Shi Bin
中科院分区：
文献类型：
--
作者：
Cheng Qing;Tang Chao-Sheng;Zeng Hao;Zhu Cheng;An Ni;Shi Bin
干燥开裂对土的水力力学特性有重要影响。以往的研究大多集中在浆状土样的干燥开裂，而很少有人关注压实土。本研究旨在探讨微结构对压实贫黏土干燥龟裂之影响。将5个土样分别按12.5%、14.5%、16.5%（最佳含水量）、18.5%和20.5%的含水量混合，压实成不同的初始土样微结构。压实后，土壤样品进行饱和，然后进行相同的干燥过程。通过压汞法（MIP）测试表征了每个土样的孔径分布。在干燥过程中的水分含量和表面裂纹图案的演变进行了连续监测。试验结果表明，压实过程中含水量的增加对土的微观结构和干裂特性有显著影响。随着压实含水量由干侧向湿侧的增加，土体微观结构由团聚体结构向分散体结构过渡，孔隙尺寸分布由双峰型向单峰型转变。对于具有团聚体结构的土，干燥裂缝同时萌生，并在土体中均匀分布。随着含水量的降低，裂缝几何参数如表面裂缝率和裂缝密度几乎呈线性增加。相比之下，对于分散结构的土壤，更多的本地化增长的初级和次级裂纹观察和裂纹的几何参数表现出两个阶段的线性增长过程中干燥。这项研究提供了微观结构的解释压实粘土干燥开裂的重要方面，并可能指导岩土工程应用的粘土材料的设计。
Desiccation cracking has a significant influence on the hydro-mechanical behaviour of soils. Most previous studies focus on the desiccation cracking of slurry soil samples, whereas little attention has been paid to compacted soils. This study aims to investigate the effects of microstructure on the desiccation cracking of a compacted lean clay. Five soil samples are mixed with different water contents including 12.5%, 14.5%, 16.5% (optimum water content), 18.5%, and 20.5%, compacted to generate different initial soil microstructures. After compaction, the soil samples are subjected to saturation and then the same drying process. The pore size distribution of each soil sample is characterized by performing mercury intrusion porosimetry (MIP) test. The change in water content and the evolution of surface crack pattern during the drying process are continuously monitored. Experimental results show that the addition of water content during soil compaction significantly influences the microstructure and desiccation cracking behaviour of soils. With increasing compaction water content from the dry side to the wet side of the optimum water content, soil microstructure transits from an aggregate structure to a dispersed structure, resulting in the change of pore size distribution from bimodal to unimodal. For soils with aggregate structures, the desiccation cracks initiate simultaneously and distribute uniformly throughout the soil body. With decreasing water content, crack geometrical parameters such as surface crack ratio and crack density increase almost linearly. Comparatively, for soils with dispersed structures, more localized growth of primary and secondary cracks are observed and the crack geometrical parameters show a two-stage linear growth during drying. This study provides microstructural interpretations to important aspects of desiccation cracking in compacted clayey soils and may guide the design of clay materials for geotechnical engineering applications.