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斥水红黏土的增湿强度特性研究
杨松,吴玉琴,吴培军,周明凯
云南农业大学 水利学院
摘要:
斥水土壤减少水分入渗,影响农作物生长一直被视为不利之处,然而从力学稳定的角度看,减少甚至阻止雨水入渗可以使土壤保持非饱和状态,维持其强度,这对土体结构的稳定性是有利的。在红黏土中加入十八胺使其由亲水变为斥水,分别对亲水和斥水土进行不同干密度下增湿和不增湿直剪试验,通过试验对不增湿条件下红黏土由亲水变为斥水后的抗剪强度变化规律及增湿对亲水和斥水红黏土抗剪强度的影响展开研究。试验结果表明:不增湿条件下,亲水土壤变为斥水后其强度会降低,且随着正应力的增大斥水土壤抗剪强度降低越明显,增湿对亲水土壤影响较大,而对斥水土壤的影响则较小。随着干密度的增大,亲水与斥水土的抗剪强度都会增大,增湿对两类土壤的影响随着干密度和正应力会发生改变,利用土壤的斥水特性来提高土壤增湿条件下的抗剪强度时,需要综合考虑土壤的干密度及所处的应力状态。
关键词:  斥水土  抗剪强度  增湿  干密度
DOI:
分类号:S147.2
基金项目:国家自然科学(41867038, 41662021)
Study on Wetting Strength Characteristics of Water repellencyRed Clay
YANGSONG1, Wu Yuqin2, Wu Peijun2, Zhou Mingkai2
1.College of Water Conservancy,Yunnan Agricultural University;2.College of water conservancy, Yunnan Agricultural University
Abstract:
Repellent soil reduces water infiltration and thereby affects crop growth. Such characteristic is widely accepted as a disadvantage of repellent soil. However, repellent soil can maintain its unsaturated state and strength through reduction and even prevention of rain infiltration, which are conducive to the stability of soil structure from the perspective of engineering geology. In this study, octadecylamine was added into red clay to change its state from hydrophilic into repellent. Direct shear tests on hydrophilic and repellent soils with and without wetting were carried out under different dry densities. Moreover, the variation rules in the shear strength of red clay without wetting during the transition from hydrophilic soil to repellent soil were investigated. The influences of wetting on the shear strengths of hydrophilic and repellent soils were tested. Results demonstrate that shear strength of repellent soil without wetting is lower compared with that of hydrophilic soil and that such reduction amplitude increases with the increase in normal stress. Wetting considerably influences the shear strength of hydrophilic soil but only slightly affects that of repellent soil. The shear strengths of both hydrophilic and repellent soils increase with the increase in dry density. The influences of wetting on hydrophilic and repellent soils are related to dry density and normal stress. Thus, comprehensive considerations should be given to the dry density and stress state of soils when improving the shear strength of wetting soils based on the characteristics of repellent soils.
Key words:  repellent soil  shear strength  wetting  dry density

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