Welcome to the Getting Started with GeoStudio video series.
This tutorial introduces how to use of the AIR/W product of GeoStudio 2012.
This tutorial video has been designed to help walk new users through the basics of setting up a simple air flow analysis in AIR/W.
So, if you are new to AIR/W,
and are not sure where to start, you have come to the right place.
The main topics that will be covered in the tutorial will be how to create an analysis in AIR/W
by using: the define view to set up the analysis;
the solve manager to solve the numerical analysis;
and the options available in results view to gain a deeper understanding of the analysis.
If you are not familiar with GeoStudio Products, it is recommended that you start with the tutorial videos for SEEP/W,
SIGMA/W or SLOPE/W
to gain an understanding of the tools available
for drawing your geometry domain,
creating sketches, or explanations on basic options that are available in all GeoStudio Products.
This tutorial video will mainly discuss AIR/W options and tools
where they differ from SEEP/W, SIGMA/W,
or SLOPE/W.
Note AIR/W is used in conjunction
with SEEP/W or TEMP/W
to model the flow regime
prior to modelling the air flow problem.
So, let's get started.
This example will include two analyses. The first will be a steady state water transfer analysis using
SEEP/W to determine how much water will flow into a tunnel
that is located below the regional water table.
The second analysis will illustrate
how much water will flow into the same tunnel if the air in the tunnel is pressurized to 50 kPa.
We will start with a steady state water transfer analysis already created
with our ground region and tunnel already drawn.
If you are unsure of how to use the visualization sketching tools or draw the
geometry regions, please refer to the Sketching Tools and Geometry video tutorial
or the introduction tutorial videos to SEEP/W, SIGMA/W or SLOPEW.
Now we will add the material to our analysis.
I will go to KeyIn, materials to open the materials define window.
I will add a new material and give the material a name.
I will then choose the saturated-unsaturated option from the drop down menu.
Here I can create a hydraulic conductivity and volumetric water content function for my material.
More information on the hydraulic model options
can be viewed in the SEEP/W: Estimating hydraulic functions tutorial video.
We will first add the volumetric water content function
by clicking on the ellipsis button.
We will simply add a volumetric water content function
for a silty clay sample material
with a saturated water content or porosity
of 0.47.
I will also include a coefficient of volume compressibility value
of 1E-4.
Next, I will add a hydraulic conductivity function by clicking on the appropriate ellipsis button.
I will add a function using the silty clay volumetric water content function
and a saturated hydraulic conductivity of 0.01 m per day
and a residual water content of 0.05.
Now we will add the material to our domain by choosing draw materials.
We will simply choose the silty clay material and assign it to our soil region.
We will not apply any material properties to the tunnel, as it is considered to be an open circular region.
Boundary conditions can be created and assigned in a similar way as the materials.
I will choose KeyIn, boundary conditions to open the define boundary conditions window.
The potential seepage face and zero pressure boundary conditions are created by default.
I will also add a new hydraulic boundary condition to represent the regional water table height at the far-field boundaries.
I will use the total head boundary condition with a constant value of 16 m.
Now, I can add the boundary conditions to my domain to represent the water table on the far-field boundaries
and the seepage face along the surface of the tunnel.
Now we are ready to add our coupled air flow analysis to the analysis tree.
We will go into the KeyIn analyses window
and clone the current water transfer analysis.
We will simply change the name of our analysis and activate air flow on our domain.
The geometry of the domain is considered project specific, but the material properties, boundary
conditions, and analysis type can be modified to simulate different scenarios of the analysis.
Now we must return to our define window and set up the air flow properties for our analyses.
We will go into the KeyIn materials define window
and clone the current material.
This material will include the same volumetric water content and hydraulic conductivity functions
as the water transfer only analysis,
but we will now add an air conductivity function to help define air flow within the domain.
We will click on the appropriate ellipsis button and estimate the air function.
We will use the silty clay volumetric water content function and an air conductivity of 1 m per day.
Now we can add this material to the domain for the tunneling with air flow analysis.
Now we are ready to define our boundary conditions. We will go to KeyIn,
boundary conditions.
The default boundary condition of the zero atmosphere pressure is already added to the boundary conditions list.
We will add a constant pressure boundary condition to simulate the pressurized air within the tunnel and change the value to 50 kPa.
We will add the zero atmosphere pressure boundary condition to the surface of the soil domain and the
tunnel pressure to the line representing the outer rim of the tunnel.
If at any time you wish to only see the air flow boundary conditions on the domain
and remove the hydraulic boundary conditions from the visualization,
you can change the drop down menu from all to air.
Note, the hydraulic boundary conditions are still applied to the domain,
but are simply not a part of the visualization.
Our next step will be to look at the default mesh. We can see that a default global element size is set to 1 m.
We will refine the mesh by changing this value to 1.25 m.
We will also click on the perimeter line of the tunnel and change the element size to be half of the default element length.
More information on the meshing options can be found in the engineering books or the Mesh options and constraints tutorial video.
Now we can solve all of our analyses
by clicking on the start button in the solve manager.
Once solved, the window will automatically change to the results view instead of the define view.
By default, the total head contours will appear along with the phreatic surface as a blue dashed line.
You can change the contours that are being shown on the domain in the results window by choosing a different contour type in the drop down menu.
You can also add new contour options by clicking on the draw contours button.
You can change the shading methods used to draw your contours,
add a legend,
or change the increments and starting and ending values of your contours.
Other items can be added by clicking on the add button and choosing the type of results contour you would like to create.
We will go to our second analysis to view the pore-water pressure contours when the air pressure is added to the tunnel.
We will go back into the draw contours window and add a new contour item.
Here, we will add the matric suction contours to the list for the air flow analysis.
Currently, we can only see the water velocity vectors on the domain.
We can go to draw, velocity vectors, to add the air velocity vectors to the domain as well.
You can also add labels to your contours using the draw contour labels button and clicking on the contour lines where you want labels to be painted.
You can choose what items are activated in the results window at any time using
the view preferences toolbar along the right side of the screen.
Here you can toggle on and off results information,
such as the velocity vectors, contours,
or you can view your mesh, boundary conditions, material properties,
or toggle on and off geometry items, such as the regions or point numbers.
Next we will create a graph to help us gain a better understanding of our analysis.
By default, for all SEEP/W analyses,
the conductivity vs. matric suction graph shows that the resulting conductivity matches the hydraulic conductivity function
that was entered in the KeyIn materials define window.
This is one of the checks on convergence. More information on convergence graphs can be found in
the engineering books or the SEEP/W: convergence and under-relaxation tutorial video.
We will add a graph that shows the total rate of discharge of water through the walls of the tunnel.
We will choose our node locations to be along the perimeter of the tunnel line.
We will choose water flow,
water flux vs. time,
and toggle on the sum Y vs. average X option.
Now we can see that the total discharge through the tunnel when there is air pressure
is equal to approximately 0.076 m³ per day.
Note, the negative sign here indicates that water is leaving the domain.
When we change to the first analysis where air pressure was not added to the tunnel,
we can see that the discharge increases to 0.144 m³ per day.
More information on the other options available in the results view can be viewed in the SEEP/W, SIGMA/W,
or SLOPE/W tutorial videos.
We have now reached the end of this introductory tutorial.
Note that not all of the powerful features of AIR/W 2012
have been used or discussed here.
Further information on each command can be found in the online help, supporting documentation for AIR/W,
as well as in other tutorial videos of the Getting Started with GeoStudio video series.
Thank you for watching.