Underground Tunnels

1.0 Introduction

This tutorial will demonstrate some of the consolidation features of RS3. Here we create multiple layers of embankment on multiple layers of soil using boreholes. All tutorial files installed with RS3 can be accessed by selecting File > Recent > Tutorials folder from the RS3 main menu. The finished product of this tutorial can be found in the Underground Tunnels.rs3v3 file. The starting file can be found in Underground Tunnels - starting file.rs3v3 file.

2.0 Starting the Model

1. Select File > Recent > Tutorials in the menu.
   
2. Open the starting file Underground Tunnels - starting file.rs3v3.

All the project settings and material definitions are predefined in the starting file. Read through these two sections to make sure the inputs in the model are consistent with this tutorial.

3. Select: Analysis > Project Settings
4. The Project Settings dialog is used to configure the main analysis parameters for your RS3 model. In Units tab, set Units = Metric, stress as MPa.
   
5. Next, select the Groundwater tab.
   
6. Check Method = None and click OK to close the dialog.

3.0 Import Examine3D File

Importing the Tunnel Geometry

1. Select: File > Import > Import Examine3D file.
2. Select UndergroundTunnels.ex3 (from the tutorial folder File > Recent > Tutorials > Underground Tunnels - starting file), ensure that when selected in the visibility pane, that in the properties pane for the underground tunnels, the Role = Excavation, and Applied Property = No Material.

4.0 Defining External Box

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

1. Select: Geometry > Create External Box.
2. A Create External dialog will open. Enter Expand by = 2 for all of X, Y, and Z, press [Update Preview] to update the selection. Then click OK.

5.0 Defining Material Properties

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

The starting file should already have these values provided for the user. Just make sure the values in these tutorials are consistent with the model.

1. Select: Materials > Define Materials.
2. The import should have brought the material properties from the Examine3D model. Select [Examine3D – AECL Underground Research Laboratory Material], and ensure the following properties are entered in the [Strength] and [Stiffness] tabs respectively.

Material 1:

6.0 Divide All Geometry

Now we can cut into the external box with the tunnels:

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



2. Click OK to close the dialog.
3. Select the external box in the visibility pane, and in the properties pane change the Role = Geology, Applied Property = Examine3D AECL Underground Research Laboratory Material.

Your model should now appear as below:

7.0 Adding Stress Loading

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

1. Select: Loading > Field Stress.
2. Check the following field stress, the imported geometry should have this condition as shown below:



• Field Stress Type = Constant
  
• Sigma 1 = 60 MPa
  
• Sigma 2 = 50 MPa
  
• Sigma 3 = 15 MPa
  
• Defined by = Trend & Plunge
  
• Sigma 1 (Trend, Plunge) = (117,0)
  
• Sigma 3 (Trend, Plunge) = (0, 90)
  
3. Click OK.

8.0 Setting Boundary Conditions

Adding Model Restraints

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

RS3 has a built-in “Auto Restrain” tool for use on underground models.

2. Select: Restraints > Auto Restrain (Underground). You should see the restraints on the model as shown below:

This completes the construction of the model (in terms of geometry).

9.0 Meshing

Configuring and Calculating Mesh

1. Next, we move to the Mesh workflow tab.
2. Select: Mesh > Mesh Settings
3. Enter Element Type = 4-Noded Tetrahedra, and Mesh Gradation = Graded.
   
4. Click Mesh to mesh the model.

The mesh is now generated, your model should look like the one below.

10.0 Computing Results

Next, we move to Compute workflow tab. From this tab, we can compute the results of our model.

1. Save your model by selecting File > Save As. Enter a new file name and click Save.
2. Next, you need to save the compute file: File > Save Compute File. You are now ready to compute the results.
3. Select: Compute > Compute

11.0 Interpreting Results

11.1 Displaying the Results

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

1. 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:

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

2. Select: Interpret > Show Excavation Contour

We also want to define a plane that goes through the slanted cross tunnel. First, we must define a plane,

3. Select: Interpret > Show Data on Plane > XY Plane
4. In the Create Plane dialog, check if the default setting is in center coordinates as shown below. If not, enter: Center of (x, y, z) = (-16.0675, -13.7231, 1.285), Normal Vector of (x, y, z) = (0, 0, 1), then press OK.

11.2 Total Displacement

In the top right corner of the Results tab, ensure Element = Solids, and change Data Type = Solid Displacement > Total Displacement:

This concludes the Underground Tunnel tutorial.