Assessment of the hydraulic characteristics of unsaturated base-course materials: a practical method for pavement engineers

2003 ◽  
Vol 40 (1) ◽  
pp. 121-136 ◽  
Author(s):  
J Côté ◽  
J -M Konrad
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Characteristic Curve ◽  
Practical Method ◽  
Hydraulic Characteristics ◽  
Soil Water Characteristic Curve ◽  
Uniform Dispersion ◽  
Distribution Index ◽  
Graded Material ◽  
Base Course

This paper presents the results of a comprehensive laboratory investigation program on the influence of the properties of fines particles on the hydraulic characteristics of granular base-courses. The soil-water characteristic curve and the hydraulic conductivity were determined for three types of well-graded crushed aggregates (granite, limestone, and schist) with different amounts of fines (3.5–12.5%). A porosity model that considers the uniform dispersion of fines is proposed for well-graded material. Empirical relationships have been developed between the hydraulic parameters (i.e., the saturated hydraulic conductivity, the air entry value, the pore-size distribution index, the fines fraction porosity) and their specific surface area. A methodology is proposed for the assessment of the saturated and unsaturated hydraulic characteristics of base-course materials.Key words: pavement, drainage, base-course, fines, soil-water characteristic curve, hydraulic conductivity.

scholarly journals Effects of Temperature Change on the Soil Water Characteristic Curve and a Prediction Model for the Mu Us Bottomland, Northern China

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1235
Author(s):  
Xiaoying Qiao ◽  
Shaoyang Ma ◽  
Guixing Pan ◽  
Guanglu Liu
Keyword(s):  
Hydraulic Conductivity ◽  
Prediction Model ◽  
Soil Water ◽  
Direct Measurement ◽  
Empirical Formula ◽  
Characteristic Curve ◽  
Soil Column ◽  
Distribution Model ◽  
Undisturbed Soil ◽  
Soil Water Characteristic Curve

The soil-water characteristic curve (SWCC) is the basis for obtaining the hydraulic conductivity parameters of a soil as well as for using soil water and heat transport models. At present, the curve can be obtained by two methods: by direct measurement and by empirical formula. Direct measurement is both difficult and time-consuming. By contrast, fitting the SWCC with a suitable empirical formula is stable and convenient. The van Genuchten (VG) model has the advantage of universal applicability due to its use of a statistical aperture distribution model for estimating hydraulic conductivity. This study selected the Mu Us Bottomland as a study area. Data on the water content and water potential of undisturbed soil from this site were obtained with a Ku-pF instrument and a self-designed soil column experiment with temperature settings of 13 °C, 18 °C, 23 °C, 27 °C, and 30 °C. The variation of four main parameters in the VG model with temperature was analyzed based on thermodynamic theory and considering the effect of temperature on soil capillary pressure via its effects on surface tension and contact angle. A prediction model for the soil-water characteristic curve of the Mu Us Bottomland was then constructed, and its applicability was further analyzed. The temperature dependence of the SWCC demonstrated here provides an important scientific basis for agricultural production, farmland water conservancy, and the design of soil and water conservation engineering projects.

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