Abstract

Soil-water characteristic curve (SWCC) that represents the relationship between the soil moisture and matric suction is one of the important constitutive models required for numerical modeling of unsaturated soils. An effective SWCC model should be capable of calculating the moisture-suction variation for the entire range of degree of saturation. Applicability of popular SWCC models such as Brooks and Corey, van Genuchten, and Fredlund and Xing is limited, especially in low (< 20%) degree of saturation range. In this study, all these models are modified by incorporating maximum suction as one of the model parameters, so that these models can be effectively used over the entire range of degree of saturation. The Fredlund et al (1994) permeability function is also modified based on the modification to the Fredlund and Xing SWCC model. The applicability of the improved models is investigated by calibrating the SWCC of various types of soil and presented in this paper. Based on this study it can be concluded that the modified models are flexible enough to fit the experimental data for the entire range of degree of saturation.

Highlights

  • Unsaturated soil is a three phase porous media consisting of three bulk phases: solid skeleton, water, and pore air

  • Soil-water characteristic curve (SWCC) that represents the relationship between the soil moisture and matric suction is one of the important constitutive models required for numerical modeling of unsaturated soils

  • Applicability of popular SWCC models such as Brooks and Corey, van Genuchten, and Fredlund and Xing is limited, especially in low (

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Summary

Introduction

Unsaturated soil is a three phase porous media consisting of three bulk phases: solid skeleton, water, and pore air. In addition to these three bulk phases, there exist three interfaces: solid-water interface, solid-air interface, and water-air interface. The water-air interface known as contractile skin that does not exist in either saturated or dry soil influences the flow and mechanical behavior of unsaturated soil. The contractile skin maintains the pressure balance between water and air phases. The difference between the air pressure and water pressure is known as matric suction

Soil Water Characteristic Curves
Relative Permeability Functions
Improved SWCC Models and Comparisons
Predictive Capability of the I-F-X Model
Modified Permeability Function and Comparisons
Conclusions
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