基于核磁共振干湿循环影响下土壤斥水性分析

李同海; 赵仕

doi:10.19720/j.cnki.issn.1005-9369.2021.06.007

基于核磁共振干湿循环影响下土壤斥水性分析

李同海¹,
赵仕²

1. 中铁十七局集团有限公司;
2. 华南理工大学土木与交通学院

基金项目:

国家自然科学基金项目(51909095)

详细信息

作者简介:
李同海(1974-),男,高级工程师,研究方向为路基工程及土壤渗流特性。E-mail:yang_jy2016@163.com

中图分类号: S152.7
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出版历程
- 刊出日期: 2021-06-24

Analysis on soil water repellency under influence of dry-wet cycle based on NMR

LI Tong-hai¹,
ZHAO Shi²

1. China Railway 17th Bureau Group Co., Ltd.;
2. School of Civil Engineering and Transportation, South China University of Technology

摘要

摘要: 为探究干湿循环对土壤斥水性的影响,揭示斥水性随含水率变化内在机理,测定1～3次干湿循环过程中水滴穿透时间（WDPT）和不同含水率土壤核磁共振（T₂）曲线,建立孔隙水分布与WDPT内在联系。结果表明,随土壤含水率增加,WDPT值先增后减;相同含水率下,吸湿过程WDPT值略高于脱湿过程;1次循环后,土壤斥水性出现大幅衰减（减小65%以上）。含水率减小,T₂曲线积分面积和峰值均随之减小;含水率低于17.1%时,T₂曲线最大值明显减小。研究发现,干湿循环不会改变土壤斥水性对含水率的依赖;给定相对湿度下,孔径大于临界孔径rC的孔隙水同时开始蒸发,较大孔隙内水首先蒸发;孔隙内"填充气"变化是导致土壤斥水性对含水率依赖的主要原因。
- 干湿循环 /
- 斥水性 /
- 核磁共振 /
- “填充气”
Abstract: This study explored the effect of dry-wet cycle on soil water repellency, and revealed the internal mechanism of water repellency changing with water contents. The water drop penetration time（WDPT） during 1-3 dry-wet cycle was tested, and the change law of soil water repellency in the process of drying and wetting was analyzed; the T2 curve of specimen under different water contents in drying process was also measured to establish the internal relationship between pore water distribution and WDPT. The results showed that the WDPT of soil first increased and then decreased with the increase of water content; under the same water content, the WDPT during the moisture absorption process was slightly higher than that during the dehumidification process; the soil water repellency decreased significantly（more than 65%） after one cycle. The integral area and peak value of T2 curve decreased with the decrease of water content; the maximum value of T2 curve decreased significantly when the water content was less than 17.1%. This study found that dry-wet cycle did not change the dependence of soil water repellency on water content; at a certain relative humidity, the evaporation of water in the pore with pore size larger than rCoccurred simultaneously, but the water in the larger pores finished this evaporation first. The change of "filling gas" was the main reason that caused the dependence of soil water repellency on moisture content.
- dry-wet cycle /
- soil water repellency /
- nuclear magnetic resonance（NMR） /
- "filling gas"

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