Comparative study of soil water characteristic curve prediction methods

Ahmadiadli, Mohammad
Huvaj Sarıhan, Nejan
Toker, Nabi Kartal
Kürkçü, Mefküre Gamze
The soil-water characteristic curve (SWCC), which defines the relation between soil suction and water content, plays a key role in geotechnical studies of the unsaturated soils. Some researchers such as Brooks & Corey (1968), Van Genuchten (1982) and Fredlund& Xing (1994) have proposed curve fitting equations for SWCC. Fitting equations to the laboratory test data obtained from direct measurement of water content versus changes in matric suction is the most reliable method, but it is expensive and time consuming. Alternatively, there are indirect approaches, which estimate SWCC based on the particle size distribution (PSD) in granular soils and plasticity index in fine grained soils. In this research, we are presenting the drying SWCC of five different soils obtained from laboratory pressure plate and hanging column tests (according to ASTM D 6836, methods A & C), together with application of (1) curve-fitting methods, and (2) SWCC estimation methods based on particle size distribution and plasticity index, proposed in the literature. The materials used in this study are a sand specimen, a specimen of silt and three specimens of clay. We compare different curve-fitting methods and predicted SWCCs with the laboratory data. We found that except Gardner (1958), curve-fitting methods can successfully model the SWCC. We also concluded that any of Fredlund& Wilson (1997), Scheinost (1996), Vereecken (1989) and Arya& Paris (1981) pedo-transfer functions (PTFs) can predict the SWCC somewhat better than the rest of the prediction methods in any of the five soils and none of them is the single best for all these soils.


Obtaining soil-water characteristic curves by numerical modeling of drainage in particulate media /
Shoarian Sattari, Amir; Toker, Nabi Kartal; Department of Civil Engineering (2014)
The soil water characteristic curve (SWCC) reflects fundamental drainage properties of partially saturated soils by revealing the relation between soil suction and water content. Although during the past decades, various experimental methods have been proposed for obtaining the SWCC, these approaches are generally time consuming, expensive and highly dependent on operator skills. One solution to this has been sought through various empirical or physico-empirical formulations that link the SWCC to common soi...
Assessment of core-filter configuration performance of rock-fill dams under uncertainties
Çalamak, Melih; Yanmaz, Ali Melih (American Society of Civil Engineers (ASCE), 2018-04-01)
Probabilistic analyses are conducted for seepage through a rock-fill dam having two different core-filter configurations: one sloping and the other a central symmetrical core-filter arrangement. Uncertainties in core and filter are considered, assuming their hydraulic conductivities as random variables. For this purpose, finite-element software used for groundwater flow and seepage analyses is coupled with a random-number-generation algorithm. Monte Carlo simulations are performed for probabilistic seepage ...
Exponential Equation for Predicting Shear Strength Envelope of Unsaturated Soils
Ahmadi Naghadeh, Reza; Toker, Nabi Kartal (2019-07-01)
An exponential equation is introduced to predict the nonlinear variation of shear strength with matric suction for unsaturated soils. The proposed equation involves three constant parameters, two of which are effective shear strength parameters (i.e., phi ' and c '). The third parameter is the maximum capillary cohesion, c '' max, which is the maximum possible increase in shear strength due to matric suction. A procedure for the determination of c '' max from the soil-water characteristic curve (SWCC) is de...
Effective Stress and Shear Strength of Moist Uniform Spheres
Toker, Nabi Kartal; Culligan, Patricia J. (Wiley, 2014-05-01)
In continuum soil mechanics, the mechanical behavior of an element of soil is related to the effective stress, which is a measure of the average stress transmitted through the solid matrix in the form of contact stresses. In unsaturated soils, the coexistence of water and air within the soil pore space complicates this concept because the microscopic distribution of each fluid phase in soil pores cannot be known. Because it is thus not possible to physically measure effective stress in unsaturated soils, it...
Determination of soil hydraulic properties using pedotransfer functions in a semi-arid basin, Turkey
TOMBUL, MUSTAFA; Akyürek, Sevda Zuhal; ŞORMAN, ALİ ÜNAL (2004-12-01)
Spatial and temporal variations in soil hydraulic properties such as soil moisture 0(h) and hydraulic conductivity K(theta) or K(h), may affect the performance of hydrological models. Moreover. the cost of determining soil hydraulic properties by field or laboratory methods makes alternative indirect methods desirable. In this paper, various pedotransfer functions (PTFs) arc used to estimate soil hydraulic properties for a small semi-arid basin (Kurukavak) in the north-west of Turkey. The field measurements...
Citation Formats
M. Ahmadiadli, N. Huvaj Sarıhan, N. K. Toker, and M. G. Kürkçü, “Comparative study of soil water characteristic curve prediction methods,” 2012, Accessed: 00, 2021. [Online]. Available: