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On-line Access: 2019-08-05

Received: 2019-04-23

Revision Accepted: 2019-06-20

Crosschecked: 2019-07-08

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Citations:  Bibtex RefMan EndNote GB/T7714

 ORCID:

Qian Zhai

https://orcid.org/0000-0003-4619-2821

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Journal of Zhejiang University SCIENCE A 2019 Vol.20 No.8 P.627-633

10.1631/jzus.A1900166


Effect of segments of soil-water characteristic curves on the estimated permeability function using statistical methods


Author(s):  Qian Zhai, Chen-feng Zhang, Guo-liang Dai, Xue-liang Zhao

Affiliation(s):  Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing 210096, China; more

Corresponding email(s):   101012332@seu.edu.cn

Key Words:  Permeability function, Statistical methods, Estimation, Soil-water characteristic curve


Qian Zhai, Chen-feng Zhang, Guo-liang Dai, Xue-liang Zhao. Effect of segments of soil-water characteristic curves on the estimated permeability function using statistical methods[J]. Journal of Zhejiang University Science A, 2019, 20(8): 627-633.

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T1 - Effect of segments of soil-water characteristic curves on the estimated permeability function using statistical methods
A1 - Qian Zhai
A1 - Chen-feng Zhang
A1 - Guo-liang Dai
A1 - Xue-liang Zhao
J0 - Journal of Zhejiang University Science A
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PB - Zhejiang University Press & Springer
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DOI - 10.1631/jzus.A1900166


Abstract: 
The water flow in unsaturated soil is controlled mainly by the soil-water characteristic curve (SWCC) and the coefficient of permeability of the soil, both of which are functions of the soil suction. Experimental measurement of both the SWCC and permeability function is time consuming and costly. As a result, indirect methods for estimating the permeability function from the SWCC are commonly accepted by researchers. Among different indirect methods for the estimation, statistical methods have been proven to be rigorous and reliable. They provide discrete results for the permeability function corresponding to different soil suctions, and the estimations are dependent on the division of SWCC segments. In this paper, we adopt two approaches with different procedures to estimate the permeability function using statistical methods. The first approach evenly divides the SWCC in the domain of volumetric water content, and the second evenly divides the SWCC in the domain of matric suction. The effects of the SWCC segments on the permeability function estimated from the SWCC (including unimodal and bimodal curves) using both approaches are investigated and discussed. A minimum number of 40 segments is recommended for the estimation. We recommend that the SWCC should be divided within the matric suction domain rather than the volumetric water content domain for the estimation of the permeability function using statistical methods.

The Authors investigated the required number of divisions to obtain a good performance of the equation in the estimation of the unsaturated hydraulic conductivity. The study will benefit engineers in practice since the direct measurement of the unsaturated hydraulic conductivity is tedious and time-consuming.

水-土特征曲线的分段对估测非饱和渗透系数的影响

目的:在采用统计法估测非饱和渗透系数的过程中,探讨水-土特征曲线分段的不同方法和不同数量对估测结果的影响.
创新点:比较在体积含水量区间和土吸力区间分割水-土特征曲线对估测非饱和渗透系数的影响; 最终建议在土吸力区间分割水-土特征曲线.
方法:采用现有模型和数学公式,对比不同类型土质(单峰和双峰水-土特征曲线)估测和实验测量的非饱和渗透系数.
结论:1. 传统的在体积含水量区间分割水-土特征曲线会造成对低吸力区域的非饱和渗透系数的估测不够精确. 2. 综合比较单峰和双峰的水-土特征曲线及2种不同分割水-土特征曲线的方法,发现在分段大于40片时,估测结果非常接近实验结果. 因此,在采用统计法估测土体的非饱和渗透系数时,建议在土吸力区间对水-土特征曲线进行分割,且分割数量应该大于40.

关键词:渗透方程; 统计法; 间接法; 水-土特征曲线

Darkslateblue:Affiliate; Royal Blue:Author; Turquoise:Article

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