Estimation of Saturated/Unsaturated Soil Properties

SoilVision Overview

Computer modeling of soil processes has grown significantly in recent years. Saturated and unsaturated soil processes can be readily solved using currently available modeling packages. Unfortunately, users worldwide have discovered these programs are only as powerful as the input data provided to them. SoilVision assists in providing this input. Laboratory testing can be expensive and time-consuming, particularly for unsaturated soils. Generally, all that is required for engineering modeling purposes is an estimate of unsaturated soil property functions.
The modeling of unsaturated soil processes such as seepage, contaminant transport, stress, and thermal analysis all require information on unsaturated soil property functions. SoilVision provides you with the benefit of experimental data on over 5,000 soils. The knowledge of experts has also been incorporated to provide interpretation and predictive capabilities to the system.
SoilVision offers a level of estimation of soil parameters and unsaturated and saturated soil property functions never before available incorporating an easy-to-use Windows interface, a database of unprecedented detail, and a knowledge-based system. As a result, numerical modeling was never so easy!
SoilVision is a database knowledge-based system which assists in the estimation of saturated and unsaturated soil properties.
<Ι>Modeling: SoilVision provides state-of-the-art data and prediction algorithms to provide input to finite-element and finite-difference programs for modeling of seepage, stress analysis, contaminant transport, thermal analysis, and volume change of soils.
<Ι>Data Storage: SoilVision is built around a database system and therefore provides an excellent method of organizing and tracking soils data. Soil information can be stored and organized by project, texture, geographic location, or other significant fields.




SoilVision offers the most comprehensive dataset of unsaturated soils information available today. Saturated soils information is also provided as consolidation functions, saturated permeabilities, and saturated shear strength functions. Data included in SoilVision 1.0 has been gathered from a variety of sources. These sources include experimental data from published research, educational institutions, government agencies, and consulting firms. The person or organization responsible for the donation of soil information is stored in the database along with the publisher and geographic information. For example, this allows the user to select soils from research papers published by a certain author or to select soils information donated from a certain person.
A variety of types of soils information is also available. Soil information covering every USDA textural classification is available. In addition, many soils are also grouped by soil series, soil family, horizon, horizon depth, or Atterberg limits. Included in SoilVision is waste rock and mining tailings soils data obtained from research performed at the University of Saskatchewan involving mine sites.


SoilVision not only stores general soils information such as textural classification, volume-mass, Atterberg limits, soil chemistry, stratigraphic, and geographical location, but goes one step further. Experimental data from the following tests is included:

In summary, the dataset contains over 5,000 soils. This includes experimental data for 5,000 soil-water characteristic curves, 600 grain-size curves, 2,500 saturated permeabilities and 250 permeability curves.


SoilVision 1.0 provides an excellent dataset for research in saturated or unsaturated soils. Have you ever wondered if there is a correlation between certain soil parameters? Now you can know!
Comparisons can easily be made between property functions because SoilVision allows the plotting of multiple functions. An example of this is the plotting of several drying soil-water characteristic curves grouped by the same textural classification. Multiple soil property functions can also be plotted for any of the other functions represented in SoilVision.


The structure of SoilVision is consistent with the theoretical framework known as saturated/unsaturated soil mechanics. Information has been used from experts in geotechnical engineering, soil physics, soil science, agronomy, as well as other areas. This allowed implementation of the following ideas into SoilVision.


What good is a knowledge-based system if it cannot perform the common basic tasks related to volume-mass calculations? Give SoilVision any three volume-mass properties such as saturation, porosity, and specific gravity, and it will mathematically calculate all remaining volume-mass properties.


SoilVision will automatically classify your soil by either USCS (Unified System) or USDA standards for classification.


Soil mechanics is known to have a number of S-shaped property functions. To be of use, these functions must be represented mathematically as equations. To fit an equation to experimental data, its parameters are adjusted by a least-squares algorithm in SoilVision until a fit is achieved. SoilVision provides a continuous mathematical representation of all soil functions. These continuous functions provide several benefits when working with soils:
  • A continuous, smooth function provides numerical stability when using soil functions in a numerical modeling package. An example of this is that the convergence of a seepage finite-element model can be improved by using a smooth, physically realistic mathematical representation.
  • The mathematical functions used to represent soil functions are physically realistic. Equations that naturally represent soil functions eliminate unnatural 'humps' that are not representative of real-world situations and can cause numerical instability in finite-element modeling packages.
  • Soils can be grouped in the database according to curve-fitting parameters. All soil property functions in SoilVision have been fit with an equation where possible. This means that there are over 600 grain-size distributions which have been fit with an equation. The database can now be searched based on the three fitting parameters to select all soils with a grain-size within a specific 'band.'

    The following table shows the soil property functions that can be fit and the type of equation with which they are fit:

    Soil Property Function

    Mathematical Representation

    Grain-size distributionModified Fredlund & Xing
    Consolidation or compression curveModified Fredlund & Xing
    Wetting soil-water characteristic curveFredlund & Xing
    van Genuchten
    Brooks & Corey
    Drying soil-water characteristic curveFredlund & Xing
    van Genuchten
    Brooks & Corey
    Thermal conductivity curveModified Fredlund & Xing
    Frozen soil-water characteristic curveModified Fredlund & Xing
    Diffusion curveModified Fredlund & Xing


    Unsaturated soil mechanics has often been avoided in engineering practice due to its complexity and the expense of obtaining unsaturated soil property functions. SoilVision ends this confusion by implementing tested prediction algorithms to predict unsaturated soil property functions. The predictions available in SoilVision are summarized in the following table:

    Soil Property Function

    Prediction Method

    Drying soil-water characteristic curveM. D. Fredlund's Method
    Saturated permeabilityHazen's Method
    Cozeny-Carmen Method
    Permeability functionCampbell's Method
    Shear strength functionFredlund & Xing's Method
    Water storage functionDerivative of soil-water characteristic curve
    Unfrozen water content functionPatrick B. Black's Method
    Specific heat functionOmar Farouki's Method
    Thermal conductivity functionJohansen's Method
    Diffusion functionLim & Barbour's Method

    The prediction of the drying soil-water characteristic curve from the grain-size distribution and volume-mass properties is unique to SoilVision. The prediction technique allows successful estimation of the unsaturated properties of a soil knowing only the easily-measured grain-size and volume-mass mechanical properties. This is valuable due to the high cost of experimentally measuring the soil-water characteristic curve. The prediction of the soil-water characteristic curve has been found to work successfully for Sands, Silts, Loams, Clay's and a variety of other soils. Examples of the estimation of the soil-water characteristic curve can be seen below:


    The large amount of experimental data included in the system allows missing soil parameters to be statistically estimated with "rules."


    SoilVision would not be complete without a method to visualize information. A host of plotting functions allow the property functions for single soils or groups of soils to be plotted.


    SoilVision conforms to Windows standards of data transfer. Soils information can be "cut" and "pasted" or written to text or rich text files. Soil property functions can be output in equation form, parameter form, or as a series of points along the function.


    Windows 3.1/Windows 95/Windows NT and 8 MB RAM. Pentium with 16 MB recommended.

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