A study of hysteresis models for soil-water characteristic curves

2005 ◽  
Vol 42 (6) ◽  
pp. 1548-1568 ◽  
Author(s):  
Hung Q Pham ◽  
Delwyn G Fredlund ◽  
S Lee Barbour
Keyword(s):  
Soil Water ◽  
Unsaturated Soils ◽  
Engineering Practice ◽  
Characteristic Curves ◽  
Physically Based ◽  
Physically Based Models ◽  
Soil Water Characteristic Curves ◽  
Scanning Curves ◽  
Wetting Curve ◽  
Drying Curve

A review of hysteresis models for soil-water characteristic curves is presented. The models can be categorized into two groups: (i) domain models (or physically based models) and (ii) empirical models. Some models are capable of predicting scanning curves, while other models are capable of predicting the boundary wetting curve and the boundary drying curve. A comparison of the ability of five selected models to predict the boundary wetting curve showed that the Feng and Fredlund model with enhancements by Pham, Fredlund, and Barbour appears to be the most appropriate model for engineering practice. Another comparison among five physically based models for predicting scanning curves showed that the Mualem model-II gives the best overall prediction of scanning curves. The study showed that taking the effect of pore blockage into account does not always give a better prediction of hysteretic soil-water characteristic curves. A scaling method for estimating the initial drying curve, the boundary wetting curve, and the boundary drying curve is also presented in the paper.Key words: soil-water characteristic curve, hysteresis model, comparison, boundary curve, scanning curve, unsaturated soils.

Bimodal and multimodal descriptions of soil-water characteristic curves for structural soils

2013 ◽  
Vol 67 (8) ◽  
pp. 1740-1747 ◽  
Author(s):  
Shiyu Liu ◽  
Noriyuki Yasufuku ◽  
Qiang Liu ◽  
Kiyoshi Omine ◽  
Hazarika Hemanta
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Soil Water ◽  
Lognormal Distribution ◽  
Probability Density Functions ◽  
Density Functions ◽  
Characteristic Curves ◽  
Physically Based ◽  
Soil Water Characteristic Curves ◽  
Good Agreement

In the last decades several approaches have been developed to describe bimodal or multimodal soil-water characteristic curves (SWCCs). Unfortunately, most of these models were derived empirically. In the presented study, physically based bimodal and multimodal SWCC functions have been developed for structural soils. The model involved two or more continual pore series; the probability density functions for each pore series were assumed to be lognormal distribution and can be superposed to obtain the overall probability density function of the structural soils. The proposed functions were capable of simulating bimodal or multimodal SWCCs using parameters which can be related to physical properties of the structural soils. The experimental SWCC data were used to verify the proposed method. The fitting results showed that the proposed approaches resulted in good agreement between measurement and simulation. These functions can potentially be used as effective tools for indentifying hydraulic porosities in the structural mediums.

scholarly journals Effects of Contact Angle on the Hysteresis Effect of Soil-Water Characteristic Curves during Dry-Wet Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Gaoliang Tao ◽  
Ziyue Li ◽  
Lisheng Liu ◽  
Yangyang Chen ◽  
Kai Gu
Keyword(s):  
Contact Angle ◽  
Soil Water ◽  
Contact Angles ◽  
Hysteresis Effect ◽  
Filter Method ◽  
Characteristic Curves ◽  
Soil Water Characteristic Curves ◽  
High Suction ◽  
Hysteresis Characteristics ◽  
Drying Curve

The hysteresis characteristics of soil-water characteristic curves (SWCCs) under dry-wet cycling conditions are very important for understanding unsaturated soil properties, so it is crucial to propose an accurate and efficient method for predicting the hysteretic behaviors of SWCCs. To this end, this paper investigates the hysteresis characteristics of SWCCs in the full suction range of seven kinds of Hunan red clay with different initial dry densities by combination of the pressure plate method, the paper filter method, and the saturated salt solution method. It is found that there are, respectively, strong and weak hysteresis zones in the drying and wetting SWCCs under dry-wet cycling conditions. By combining this feature and based on the drying curve, the soil volume and contact angle changes during the drying and wetting processes are employed to predict the hysteretic behaviors of SWCCs. To verify the validity of the prediction method, the predicted curves of the samples with different initial dry densities are compared with the measured curves. The results show that in the strong hysteresis zone, the hysteresis characteristics of the drying and wetting SWCCs are mainly resulted from the changes in the soil pore structure; in the weak hysteresis zone, the hysteresis characteristics are mainly influenced by the changes in the receding and advancing contact angles corresponding to the drying and wetting processes. The Young–Laplace theory is used to transform the changes of contact angle during the drying and wetting processes into the proportional relationship k of matric suction, and the corresponding wetting curve is obtained by smoothing the drying curve. It is found that the prediction effect in the high suction part (the strong hysteresis zone) is better than that in the weak hysteresis zone, which confirms that the hysteresis effect of SWCCs in the high suction part is influenced by the contact angle. Our proposed method can greatly reduce the test period and has a significant practical application value, which provides a new idea for the prediction of SWCCs under dry-wet cycling conditions.

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