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干湿循环对土壤斥水性的影响
杨 松,王 磊,周明凯,马泽慧,李 铭
云南农业大学水利学院
摘要:
处于地表的各类土壤总是处于不断的干湿循环过程,土壤性质也会因此而发生改变。本文通过试验对干湿循环过程中斥水性土壤的“斥水-亲水”特性展开研究,试验结果表明:干湿循环对斥水性土壤的接触角及斥水性有重要影响。在干湿循环过程中,增湿时的初始状态不同则其初始接触角会发生变化,土壤斥水性对初始状态的敏感性随着黏粒含量的增加而增大。干湿循环开始时,土壤越干则初始接触角越大。当黏土和黏壤土试样含水量减小时,增湿或脱湿过程中滴水穿透时间(water drop penetration time,WDPT)先增加后减小,在某一时刻达到峰值,试样含水量相同时,脱湿过程所对应的WDPT要明显小于增湿过程,两种类型的土样在干湿循环中均没有临界含水量。随着含水量的降低,壤质砂土的WDPT是不断增加的,且干湿循环过程中斥水性砂土并没有出现峰值,存在明显的临界含水量。
关键词:  斥水性  接触角  干湿循环  WDPT  躺滴法
DOI:10.13758/j.cnki.tr.2019.06.021
分类号:S147.2
基金项目:国家自然科学基金项目(41662021,41867038)资助。
Effect of Drying-Wetting Cycles on Soil Water Repellency
YANG Song1, WANG Lei2, ZHOU Mingkai2, MA Zehui2, LI Ming2
1.College of Water Conservancy,Yunnan Agricultural University;2.College of Water Conservancy, Yunnan Agricultural University
Abstract:
On the earth’s surface, all kinds of soils are always in continuous drying-wetting cycles, which can result in the changes of soil properties. An experiment was conducted to study to the repellent - hydrophilic characteristics of repellent soils in drying-wetting cycles. The results showed that drying-wetting cycles had important impacts on soil-water contact angle and hydrophobicity. When the soil is in drying or wetting, different initial states caused different contact angles. As clay particles increasing, the susceptibility of soil repellency increased to initial states. At the beginning of drying-wetting cycle, the drier sample usually corresponded to the higher contact angle. As water content decreased in loam or clay soil samples in drying-wetting cycle, the WDPT increased and then decreased, and reached the maximum at a certain water content. Under the same water content, the WDPT in drying was significantly lower than that in wetting, there was no threshold water content in the two soil samples. But the WDPT of sand soil samples increased with water content decreasing, no peak appeared in the drying-wetting cycle, and had obvious critical water content.
Key words:  Water repellent soil  Contact angle  Drying-wetting cycles  WDPT  Sessile drop method

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