Characterization of water retention behavior of cracked compacted lateritic soil exposed to wet-dry cycles
Characterization of water retention behavior of cracked compacted lateritic soil exposed to wet-dry cycles
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DOI：
10.1007/s10064-023-03089-4
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发表时间：
2023-02
影响因子：
4.2
通讯作者：
Qianhong Gao;Huixin Yu;Ling Zeng;Yu-Xin Huang
中科院分区：
文献类型：
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作者：
Qianhong Gao;Huixin Yu;Ling Zeng;Yu-Xin Huang
交替降水和蒸发往往会在粘性土中产生干燥裂缝，这必然会改变土壤的保水能力。本研究旨在探讨干湿循环对压实赤红壤持水特性的影响，并进一步模拟含裂隙土的土壤水分特征曲线。将不同的干湿循环作用于压实红壤试件，使其产生干裂。进行了微观试验，以揭示土壤的微观结构变化。然后测量和分析了不同湿-干循环后的样品的SWCCs。早期的六个干湿旋回对干裂的发展贡献最大。在微观尺度上，一些土壤团聚体被分解成单独的粘土颗粒，在干湿循环中进一步丢失，产生大量的微裂缝和中孔，这是干燥裂缝发展的原因。在干湿循环条件下，由于裂隙的存在，压实砖红土的单峰向双峰转变。随着循环次数的增加，土壤的初始进气量减小，体积含水率的降低更加明显，导致土壤的保水能力减弱。在van Genuchten模型中引入Sigmoid函数，建立了双峰SWCC的经验方程，并用实验数据进行了验证。该方程可以提供连续、光滑的双峰SWCC，所有参数都具有明确的物理意义。
Alternate precipitation and evaporation often cause desiccation cracks in clayey soils, which necessarily change the soil water retention capacity. This work aimed to examine the influence of wet-dry cycles on the water retention behavior of compacted lateritic soil and further model the soil water characteristic curve (SWCC) of the soil containing cracks. Different wet-dry cycles were imposed on compacted lateritic soil specimens to produce desiccation cracks. Microscopic tests were performed to reveal the microstructural change of the soil. The SWCCs of the specimens after various wet-dry cycles were then measured and analyzed. The early six wet-dry cycles contribute most to the development of desiccation cracks. At microscale, some soil aggregates are broken into individual clay particles and further lost during wet-dry cycles, producing numerous microcracks and mesopores, which accounts for desiccation crack development. The SWCC of compacted lateritic soil changes from a unimodal form to a bimodal form under wet-dry cycles because of crack occurrences. With increasing cycle number, the first air entry value decreases and the reduction in volumetric water content becomes more evident, leading to a weaker water retention capacity of the soil. An empirical equation of the bimodal SWCC was proposed by incorporating a sigmoid function into the van Genuchten model and then verified with the experimental data. This equation can provide continuous and smooth bimodal SWCCs with all parameters having clear physical meanings.