Transient Dam

1.0 Introduction

This tutorial demonstrates some of the transient groundwater features of RS3. Here we create a dam with a changing head to examine the pressure head with time.

All tutorial files installed with RS3 can be accessed by selecting File > Recent > Tutorials folder from the RS3 main menu. The starting file of this tutorial can be found in the Transient Dam - starting file.rs3dmodel file and the finished product of this tutorial can be found in the Transient Dam.rs3dmodel file.

2.0 Starting the Model

Open the starting file from File > Recent > Tutorials > Transient Dam - starting file.rs3dmodel

The model should have initial project settings already defined for the user. Please check the following inputs:

Select: File > Save to save the project as Transient Dam.rs3dmodel.

Go to Project Setting.

Select: Analysis > Project Settings.

The Project Settings dialog is used to configure the main analysis parameters for your RS3 model.

Next, select the [Groundwater] tab.

Check that Method = Transient, and make Define pwp method by stage = activated, then Select the [Stages] tab.

Check: Number of Stages = 6, check the change in PWP method for Stages 2- 6 = Transient, with time = 2, 4, 6, 10, 50 (also see below).

Select OK to close the dialog.

3.0 Defining the Materials

Under the same tab (Geology or Excavations) you can assign the materials and properties of the model through materials setting.

The model should have the materials already defined for the user. Please check the following inputs:

Select: Materials > Define Materials.

In the [Strength] and [Hydraulics] tab respectively, check the strength parameters and hydraulics parameters.

Material 1 [Strength]:

then select [Hydraulics].

Do similarly for Material 2:

Material 2 [Initial Conditions]:

Material 2 [Strength]:

then select [Hydraulics].

Select OK to close the dialog.

4.0 Creating Geometry

Ensure the Geology tab is selected from the workflow at the top of the screen.

4.1 CREATING THE DAM PROFILE

Select: Geometry>Polyline Tools>Draw Polyline.

On the left of the screen, a Draw Polyline dialog will open.

Select Plane Orientation = XZ,

Then enter the following U, V Coordinates (press [Enter] between each pair) =

(0, 0) [Enter]

(100, 0) [Enter]

(100, 10) [Enter]

(75, 10) [Enter]

(51, 22) [Enter]

(44, 22) [Enter]

(20, 10) [Enter]

(0, 10) [Enter]

(0, 0) [Enter]

Select the green checkmark to finish the polyline.

Select “PolyLine” in the visibility pane, then

Select: Geometry > Extrude/Sweep/Loft Tools > Extrude or select Extrude icon in the toolbar.

Enter Direction (x, y, z) = (0, 1, 0), Depth = 30, and click preview to see the geometry. Select OK.

Select "Polyline_extruded” in the visibility pane,

Select: Geometry > Set as External.

4.2 SEPARATING THE DAM LAYERS

In this model, we will have a foundation with a different dam material on top. We need to draw the line that will be used to separate the materials.

Select: Geometry > 3D Primitive Geometry > Plane.

Select Plane Definition = XY Plane. Under the Plane Definition, set Plane Origin (x, y, z) = (50, 15, 10), and Plane Normal (x, y, z) = (0, 0, 1). Leave the Rotation Around Normal to 0, then press OK.

Next, we need to create two closed shapes from the plane:

Select: Geometry > 3D Boolean > Divide All Geometry.

Select OK.

After doing so, you’ll find there are two volumes, one defining the top dam, the second the base.

Select the top volume from the visibility pane and select Applied Property > Dam, and change the name to Dam.

Select the bottom volume from the visibility pane and select Applied Property > Foundation, and change the name to Foundation.

5.0 Defining Groundwater

5.1 STEADY-STATE GROUNDWATER BOUNDARY CONDITIONS

Select the Groundwater tab from the workflow at the top of the screen.

We will now define the groundwater boundary conditions.

Make sure that Stage 1 is active in the bottom stage tabs, then select from the toolbar: Faces Selection .

While holding down the [Ctrl] key, select the faces highlighted in the following image in order to apply groundwater boundary conditions (Top two surfaces of the dam, and top surface of the foundation):

Select: Groundwater > Add Groundwater Boundary Conditions

Select the pencil beside the dropdown to edit the groundwater boundary conditions to open the Groundwater Properties dialog.

Enter Name = Unknown, Type = Unknown (P=0 or Q=0), then select OK, then OK to add the BC, ensuring it is installed at Stage 1 and never removed.

While holding down the [Ctrl] key, select the faces highlighted in the following image (other two top sides of the model)

Select: Groundwater > Add Groundwater Boundary Conditions

Select the pencil beside the dropdown to edit the groundwater boundary conditions to open the Groundwater Properties dialog

Add a new groundwater boundary condition by pressing the add symbol (+) in the bottom right of the dialog.

Enter Name = TH20, Type = Total Head (H), Total Head Value = 20, then press OK to return to the Add GWBC dialog.

For the first stage, the PWP method is steady-state so we will simply add a total head to be removed at Stage 2, then select OK.

5.1.1 Transient Groundwater Boundary Condition

Select the Stage 2 [2] tab at the bottom of the RS3 window.

Select from the toolbar: Faces Selection .

While holding down the [Ctrl] key, select the faces highlighted in the following image in order to apply groundwater boundary conditions.

Select: Groundwater > Add Groundwater Boundary Conditions

Select the pencil beside the dropdown to edit the groundwater boundary conditions to open the Groundwater Properties dialog.

We need to create a whole new transient groundwater property, add a new groundwater boundary condition by pressing the add symbol in the bottom right of the dialog. Set it up as shown and press OK

Enter Name = Transient, Select Transient, Type = Total Head (H), type in Time = (0, 2, 4, 6), and Total Head = (20, 18, 16, 14), then select OK to return to the Add GWBC dialog.

We want to apply the transient condition at Stage 2 [Install at Stage Condition to Enter] until the end of analysis. Once the settings match the screenshot below, then select OK.

6.0 Adding Field Stress

Next, we go to the Loads tab. This tab allows you to edit the loading conditions.

Select: Loading > Field Stress.

Leave Settings as default. Field Stress Type is set to Gravity. Select OK.

7.0 Setting Boundary Conditions

7.1 ADDING MODEL RESTRAINS

Move to the Restraints tab to assign restraints to the external boundary of the model.

RS3 has a built in “Auto Restrain” tool for use on underground models but we can’t utilize for this tutorial because of the inclined free surface.

For custom restrain definition, select the following faces in the model (using Face Selection in the toolbar):

Select: Restraints > Add Restraints/Displacements > Restrain XY, then press OK.

Next, we will select the bottom face to restrain.

Select: Restraints > Add Restraints/Displacements > Restrain XYZ, then press OK.

8.0 Meshing

8.1 CONFIGURING AND CALCULATING MESH

Next, we move to the Mesh tab. Here we may specify the mesh type and discretization density for our model.

Select: Mesh > Mesh Settings

Use the default options:

Element Type = 4-Noded Tetrahedra, Mesh Gradation = Graded.

Select Mesh to mesh the model.

9.0 Computing Results

Next, we move to Compute tab. From this tab, we can compute the results of our model. First, save your model: File > Save As.

Use the Save As dialog to save the file, and next, you need to save the compute file: File > Save Compute File. You are now ready to compute the results.

Select: Compute > Compute Groundwater Only.

10.0 Interpreting Results

10.1 DISPLAYING THE RESULTS

Next, we move to Results tab. From this tab, we can analyze the results of our model. First, refresh the results:

Select: Interpret > Refresh All Results.

Refreshing the result allows us to plot new results of the model. Although we did not have any previous results from this model, it is good practice to refresh results before we view new contour plots.

On the top right corner of the Results tab, you should see two drop down menus:

Ensure [Solids] is selected from the Element drop down menu

We will analyze a number of different “Data Type” results. Let’s turn on the exterior contours so we can see some results:

Select: Interpret > Show Exterior Contour.

Note: Under any non-groundwater calculations, the exterior contour will not appear, as only groundwater results were computed

Pressure Head

In the top right corner of the Results tab, change data type to Pressure head. Select: Seepage > Pressure Head:

Then Select: Interpret > Contour Legend > Contour Options, to select the Custom Range, from -0.05 to 22.5, then press OK.

The pressure head results at Stage 1, 2, 3, 4, 5, and 6 are shown below respectively.

Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6

Other results such as total and excess pore pressure are available to view. This concludes the tutorial.