연구의 선진화와 생산성 향상에
필요한 최적의 소프트웨어와 컨설팅을
공급하도록 노력하겠습니다.
 
 

[Moisture flux at the ground surface significantly impacts flux in the unsaturated vadose zone]
 

Environmental impact on soil conditions

Understanding unsaturated soil mechanics is now critical for geotechnical engineers performing slope stability analyses, designing soil covers for mine or municipal waste facilities, or determining the effect of agricultural or irrigation projects on groundwater flow. Environmental conditions at the ground surface, such as precipitation, evaporation and transpiration, have been increasingly recognized as having a significant impact on soil behaviour in the unsaturated or vadose zone. In fact, “unsaturated soil mechanics may have more to do with the ground surface moisture flux conditions than it has to do with the thickness of the unsaturated soil zone” (D.G. Fredlund, Geotechnical News, Dec. 2001). So how can you determine the impact of environmental conditions on the unsaturated zone? VADOSE/W provides a solution to this problem.
 

Comprehensive and Powerful

VADOSE/W is a finite element software product for analyzing flow from the environment, across the ground surface, through the unsaturated vadose zone and into the local groundwater regime. Its comprehensive formulation allows you to analyze both simple and complex problems. For example, you can perform a simple analysis of ground infiltration due to rainfall, or you can build a sophisticated model that considers snow melt and root transpiration, as well as surface evaporation, runoff, ponding, and gas diffusion. You can apply VADOSE/W to the analysis and design of geotechnical, mining, hydrogeological, agricultural, and civil engineering projects.
 

Typical Applications

Using VADOSE/W, you can analyze 2D flux boundary problems such as:
  • Design and performance monitoring of single or multi-layered soil covers over mine and municipal waste facilities
  • Development of climate controlled pore-water pressure distributions on natural or man-made slopes for use in stability analyses
  • Determining infiltration, evaporation and transpiration rates resulting from agriculture, irrigation projects, or natural systems
  • Predicting oxygen or radon gas diffusion and decay through the vadose zone
  • 이외에 더 많은 기능들이 있습니다.
 
(큰 이미지 보기 ☞ click)
 

Features

  • Generate soil cover meshes based on cover thickness and soil type data.
  • Model complex soil cover stratigraphy, including pinchout layers.
  • Use adaptive time stepping during the solve process to help with convergence and the diurnal nature of climate boundary data.
  • Estimate soil properties based on grain size data or other input soil functions.
  • Use a scalable global climate database or enter site specific climate data.
  • Specify net solar radiation or potential evaporation as your climate data, or let VADOSE/W estimate the energy component.
  • Import and export DXF, WMF, EMF, or bitmap graphics.
  • Cut and paste data between project files and other Windows programs.
  • Undo and redo any number of previous commands.
    이외에 더 많은 기능들이 있습니다.
 

Formulation

Computing the surface flux boundary
The key to modeling the vadose zone is predicting an accurate surface boundary condition. VADOSE/W computes this surface flux boundary by coupling ground heat, mass and vapor flow with actual climate data.
VADOSE/W extends the concepts found in the popular SoilCoverⓒ program into two dimensions. Critical to the formulation of VADOSE/W is its ability to predict actual evaporation as a function of the soil water stress state, rather than simply using soil water content, drying time, or empirical user-defined relationships. Instead, VADOSE/W uses the rigorous Penman-Wilson method to compute actual evaporation as a function of soil water pressure, a stress state variable. It is the only 2D product using this state-of-the-art approach.
Actual and Potential Evaporation
Actual Evaporation (AE) is only equal to Potential Evaporation (PE) when the soil is saturated. If the soil at the ground surface is not saturated, the AE rate can be much less than the PE rate. Wilson (1990, 1994) showed that the only way AE can be predicted correctly for all soil types and climatic conditions is to base the calculation on both the negative pore-water pressures and temperatures in the ground. Wilson modified the Penman (1948) method to make the actual evaporation rate dependent on the relative humidity of the soil and the air. The relative humidity in the soil can only be known if the soil temperature and water pressure are known and solved for simultaneously. To solve this complex set of equations, it is necessary to include vapor flow in the soil.
VADOSE/W meets all these requirements, and is fully coupled in two dimensions.

Wilson, G.W., 1990. Soil Evaporative Fluxes for Geotechnical Engineering Problems. Ph.D Thesis, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Wilson, G.W., Fredlund, D.G., & Barbour, S.L. 1994. Coupled soilatmosphere modelling for soil evaporation. Canadian Geotechnical Journal, 31(2): 151-161.
Penman, H.L., 1948. Natural evapotranspiration from open water, bare soil and grass. Proc. R. Soc. London Ser. A. 193: 120-145.
Gas Transport
VADOSE/W is formulated to analyze transient 2- dimensional oxygen or radon gas diffusion, dissolution and decay in response to changing heat and moisture conditions in the ground. The gas transport analysis is carried out simultaneously with the coupled heat and mass transfer solution. This feature can be used to determine gas concentrations and mass flows into or out of the ground in response to pre-set or user input concentration boundary conditions.
 

Integrated with Other Applications

 

[Site-measured net solar radiation data can be imported if available; otherwise,
VADOSE/W uses other climate data to predict similar values for net solar radiation.]
 
Use VADOSE/W pore-water pressures in SLOPE/W
Using finite element computed pore-water pressures in SLOPE/W makes it possible to model the effects of evaporative flux on stability. For example, you can analyze changes in stability as the pore-water pressure changes over time due to the evaporative flux process. Also use VADOSE/W data in CTRAN/W contaminant transport analysis.
 

Easy to Use

A complete modeling solution
VADOSE/W utilizes the same easy-to-use, CAD-like interface found in GEO-SLOPE's popular Office suite of geotechnical software. You can even estimate the material property functions from easily measured parameters like grain-size, saturated conductivity, saturated water content, and the air-entry value. If you make a mistake, you can orrect it using
the Undo command.

To create a VADOSE/W problem:
  • Define geometry graphically with the mouse or by typing in values. Generate your finite element mesh and then add a soil cover mesh at the surface.
  • Specify material properties and climate data by pasting directly from a spreadsheet, importing from the included databases, or by typing in your own values.
  • Interactively apply boundary conditions as fully coupled to the climate, as a function of time, or as specific values for temperature, head, pressure, total or unit water flux, or a potential seepage surface.
  • Scale data automatically in order to conduct sensitivity studies or to create data suited to your specific site.
  • Define initial conditions for the analysis by drawing an initial water table and nodal temperatures or by using computed results from a previously solved problem.
 

Comprehensive Results

 

[Infiltration and ponding resulting from high rainfall event]
 
Viewing the Results
Once you have solved your evaporative flux problem, VADOSE/W offers many tools for viewing results. Generate contours or x-y plots of any computed parameter for any time steps. Velocity vectors show flow direction and rate. Transient conditions can be shown as the changing water table position over time. Interactively query computed values by clicking on any node, Gauss region, or flux section. Then export tables of results into other applications, such as Microsoft Excel or Word, for further analysis or to prepare presentations.
Computed Parameters
When VADOSE/W analyzes an evaporative flux problem, it computes data regarding:
  • Precipitation and infiltration
  • Snow accumulation and melt
  • Plant transpiration
  • Ground freezing and thawing
  • Potential and actual evaporation
  • Surface seepage, runoff and ponding
  • Groundwater recharge
Specific computed parameters include:
  • Temperature
  • Total Head
  • Pressure
  • Pressure Head
  • Boundary Flux
  • Liquid Velocity
  • Vapor Velocity
  • Ice Content
  • Water Content
  • Vapor Pressure
  • Conductivity
  • Gas Concentration / Flux
Soil surface results data includes (for each time interval, or cumulative since Day 1):
  • Precipitation
  • Net Radiation
  • Potential Evaporation
  • Actual Evaporation
  • Runoff
  • Infiltration
  • Snow Depth
  • Actual Transpiration
Water Balance data includes cumulative:
  • Precipitation
  • Runoff
  • Boundary Fluxes
  • Evaporation
  • Storage
  • Water Balance
  • Plant Transpiration
Cover layer interface results data includes:
  • Volume of liquid flow
  • Volume of vapor flow
  • Total volume across layer
  • Total gas mass across layer
 

[Comparison of down slope and up slope cumulative surface infiltration on a shallow sloped cover]
 

[Water content profiles across capillary break during a 365 day simulation in a shallow sloped cover]