Obtaining soil-water characteristic curves by numerical modeling of drainage in particulate media /

Download
2014
Shoarian Sattari, Amir
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 soil properties, through transformation calculations or within available SWCC databases. Another solution is to fit a curve onto partial SWCC data via regression analysis. A more reasonable approach both in terms of accuracy and cost could be to simulate the pore-scale drainage of soil medium with application of computer modeling techniques. This study is aims to model the drainage of soil medium through developing a computer program in MATLAB for simulating the drying SWCC. In the proposed approach, initially, a solid phase of soil structure is generated based on the particle size distribution as well as void ratio (e) of a given soil sample. Next, the volume of pore water is divided into two main portions: (i) bulk water and, (ii) liquid bridges. Assuming the inter-particle region of three adjacent particles with minimum hydraulic radius as a pore throat, the air entry pressure of each pore throat can be computed. To this end, the Young-Laplace equation is solved through a combination of the finite difference approximation and Newton-Raphson (Jacobian) numerical methods. In this simulation the amount of applied suction is gradually increased and resulting drainage scheme of bulk pores is visualized step by step. Eventually the final residual water content of bulk pores and liquid bridges after each suction increment are determined and plotted as SWCC. The usefulness of the developed computer program is verified by comparison of the obtained SWCC to those attained based on experimental and empirical techniques. The application of proposed method is limited to non-plastic soils, and is not suitable for modeling clay particles. The developed method is capable of providing SWCC, with an almost perfect level of conformity to the experimental results, in a timely manner. Moreover, it is shown that the SWCCs obtained by the proposed algorithm are much more accurate than results of the estimation methods found in the literature for a variety of real soils.

Suggestions

Comparative study of soil water characteristic curve prediction methods
Ahmadiadli, Mohammad; Huvaj Sarıhan, Nejan; Toker, Nabi Kartal; Kürkçü, Mefküre Gamze (2012-06-30)
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 cons...
Dynamic response analysis of the machine foundations on a nonhomogeneous soil layer
Aşık, Mehmet Zülfü (1999-01-01)
Real modulus of elasticity of the soil usually increases with the depth of the soil due to the increase in overburden pressure. Therefore, incorporation of the effect of the soil inhomogeneity in the formulation to obtain the response of the machine foundations is an important and a necessary step. In this paper, equations that govern the dynamic behavior of the machine foundations and consider the inhomogeneity of the elastic foundation, particularly for Gibson type soil are derived by using variational pr...
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...
Soil water content estimation from point scale to plot scale
Demir, Gökben; Akyürek, Sevda Zuhal; Department of Civil Engineering (2018)
Estimating soil moisture is crucial for understanding vadose zone and surface hydrology dynamics. In this study, soil moisture measurement is investigated by using a range of techniques spanning different spatial scales in a test basin in the south of Turkey. A cosmic ray sensor soil moisture probe (CRS) and a water content reflectometer (CS-616) have been installed for retrieving volumetric soil moisture data continuously. Lab analyses have been performed for calibrating the installed instruments and to ob...
Remote sensing of leaf equivalent water thickness and vegetation water content using shortwave infrared reflectances
Hunt, Er; Yılmaz, Mustafa Tuğrul; Jackson, Tj (null; 2008-04-28)
Vegetation water content is an important biophysical parameter for estimation of soil moisture from microwave radiometers. One of the objectives of the Soil Moisture Experiments in 2004 (SMEX04) and 2005 (SMEX05) were to develop and test algorithms for a vegetation water content data product using shortwave infrared reflectances. SMEX04 studied native vegetation in Arizona, USA, and Sonora, Mexico, while SMEX05 studied corn and soybean in Iowa, USA. The normalized difference infrared index (NDII) is defined...
Citation Formats
A. Shoarian Sattari, “Obtaining soil-water characteristic curves by numerical modeling of drainage in particulate media /,” M.S. - Master of Science, Middle East Technical University, 2014.