Tunnel with Structural Liner and Joints

1.0 Introduction

This tutorial introduces how to model and analyze an excavation of tunnel supported by structural liner which intersects with joints underground. In the model, the joints are first modelled in the soil. Then, excavation of a tunnel with structural liner support is applied. This is a thin slice model and the RS2 model will be exported for comparison of the results.

All tutorial files installed with RS3 can be accessed by selecting File > Recent > Tutorials folder from the RS3 main menu. The initial file of the tutorial can be found in Tunnel Joint Liner interaction_initial.rs3model and the finished tutorial can be found in the Tunnel Joint Liner interaction_final.rs3model file.

2.0 Starting the Model

After opening the initial file, Go to Project Settings by following the steps:

Select: Analysis > Project Settings.

The Project Settings dialog is used to configure the main analysis parameters for your RS3 model. Under the tab [Units], set Units as Metric, stress as kPa. The dialog should look as shown below:

Select the [Stages] tab. Enter Number of Stages = 2.

Select the [Stress Analysis] tab and set the Maximum Number of Iterations to 600.

Select OK to close the dialog.

3.0 Creating Geometry & Assigning Joints

Before we begin with creating extra geometry, we will first select the plane surface and set it as external.

Select the plane, then go to select Geometry > Set as external.

Now we will create a plane for joints in the soil. Select: Geometry > 3D Primitive Geometry > Create Plane.

Enter the following coordinates after selecting the down arrow for Plane Definition:

X = 50, Y = -25, Z = -9.

Plane Orientation:

Defined by: Dip/Dip direction

Dip = 20.5

Dip Direction = 90

Select OK and you will see a new inclined plane that intersects through the tunnel model as shown below:

Select the plane from the visibility tree and select Geometry > Copy (array) and copy the plane with the values provided below.

Copies = 6 and Spacing = 3.

Select OK and you will see the model below.

Before we divide all for the geometry, we have to assign the planes to joint surfaces. Select all of the planes of an array as shown below:

Select: Materials > Joints > Add Joint Surface.

Select Interface 1 and add it at stage 1. Select OK.

Now we will divide all to create external volumes.

Select: Geometry > 3D Boolean > Divide All

Use the quality setting to Custom and change to the following settings:

Feature Preservation to Medium and Remove Volume Less Than to 0.

Select OK.

You will see the volumes created.

4.0 Support

Before we apply the liner near the tunnel, we will first excavate the tunnel. under the visibility tree, select the layers with *.excavation extension and assign properties to 'No material' at Stage2.

Then, we will assign liner to the tunnel. Turn off all the layers except the excavation as shown. Make sure the select entity is selected in toolbar, then select the volumes except the tunnel.

After this is done, select the edges of the tunnel by shift + left click on the edges of the circle as shown below:

Select: Support > Lining > Add Lining

Change Install at Stage to Stage 2 and select OK. You should see the liner applied to the tunnel shown below:

5.0 Restraints

Select the restraints tab. Select one of the flat surfaces in the XZ surface. It is easier to select surface by selecting by face option and Ctrl + left click on the surface.

Select: Add restraints Y.

Then, you will see the assigned restraints. Do the same for the other surface.

Now click the rest of the surfaces on the thin sides and restrain XYZ by selecting: Restraints > Add restraint/displacement > Restraint XYZ.

Then, you will see the following restraints as shown.

6.0 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.

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

7.0 Compute

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.

8.0 Results

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

Save the model results by selecting File > Save (CTRL + S).

Use the drop-down in the top right of the screen to select your displayed results.

• Sigma 1

• Total displacement