Anchored Sheet Pile Wall

1.0 Introduction

This tutorial introduces how to model and analyze an anchored sheet pile support system in staged excavation. It uses some of the support features of RS3 such as Liner, joints and bolts for modelling sheet pile and anchors respectively. In the model, the sheet pile walls are installed first. Then, the ground is excavated in different stages. After each stage of excavation, bolts are installed. The model contains two separate layers and the geometry of the model is provided in the initial file.

This example is the extruded version of RS2 - Anchored Sheet Pile Wall. The geometry is imported and extruded in 1 meter in an out-of-plane (z) direction.

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 Anchored Sheet Pile Wall-starting file.rs3v3 and the finished tutorial can be found in the Anchored Sheet Pile Wall.rs3v3 file.

2.0 Starting the Model

After opening the initial file, go to Project Settings:

Select Analysis > Project Settings
1. The Project Settings dialog is used to configure the main analysis parameters for your RS3 model.
Under the Units tab, set Units as Metric, stress as kPa. The dialogue should look as shown below:
Select the Stages tab to view how the staging is set up.
Click OK to close the dialog.

3.0 Model Description

The model consists of clay and sand material divided into multiple geometrics. At stage Excavate/Install first bolts and Excavate/Install second bolts, the Sand_Excavate and Clay_Excavate entities become sequentially excavated by assigning No Material to its Applied Property.

Stage: Initial & Install Sheet Pile Wall
Stage: Excavate/Install First Bolts
Stage: Excavate/Install Second Bolts and Add Loads

4.0 Defining the Lining Composition

Select Support > Liners > Defining the Lining Composition.
1. In lining composition, RS3 allows you to model a composite liner with joints applied on two sides of the liner to represent the interface between liner and the solid material.
To add joints between the liner, press the up/down arrow button on the liner. As you see in this dialog, the joints are already assigned on both sides of the liner.
To see the properties of the joints or liner, select the edit icon under Edit column, which will open the property dialog as the following:

For more information on the description of the parameters, refer to the Define Liner Interface Properties or Define Liner Properties documentation.

5.0 Assigning the Lining Composition/Bolts

Before we assign the support, we will hide some volumes of the geometry to make it easier for us to assign the liner.

Select the following entities: Clay 3, Clay 4, Clay 5, Sand_Excavate, and Clay_Excavate and hide the volumes by select the icon.

5.1 Assigning Liner

Set the selection mode to Face Selection and Ctrl+Left-Click on the three surfaces facing the excavation volumes as shown. If you are unsure, switch from Visibility Tree to Visibility Selection under Visibility pane, and select Liner Surface group.
1. See Visibility Selection documentation for more information on grouping selection.
Select Support > Liners > Add Lining.
Under Staging, set Install at stage to the Install Sheet Pile Wall stage and click OK.
If you select Lining 1 entity, you will see the liner highlighted on the viewport as well as the orange bar colouring above the stages from Install Sheet Pile Wall to the end.

5.2 Defining/Assigning Bolts

Before applying the bolts to our model, we will first check the bolts properties.

Select Support > Bolts > Define Bolts.
Select the Bolt 1 and you will see the following material property shown:
Click OK. This bolt will now be assigned to the liner layer.
Select the uppermost surface whereupon liner is installed or Bolt 1 Surface Group under Visibility Selection.
Select Support > Bolts > Add Bolts to Surface. Make sure the Bolt 1 is selected under bolt properties.
1. We will assign bolt with the following material property:
  1. Trend & Plunge: -90º Trend / 20.5º Plunge
  2. Length: 8.5m
  3. Install at Stage: Excavate / Install first bolts
2. Primary path inputs are:
  1. Primary path (required): Start: (14.34 12.17 4.83) and End: (14.34 13.37 4.82)
  2. Primary Spacing (m): 1
  3. Primary Offset (m): 0.5
  4. Secondary Spacing (m): 0
  5. Secondary Offset (m): 0
Make sure to click Preview Pattern, then click Add.
1. We will now assign the next layer of bolts. Make sure the selection mode is back to Face Selection.
To see the installed bolt, select Excavate/Install first bolts stage.
Select the surface below of which the first bolt was installed or Bolt 2 Surface Group under Visibility Selection.
Select Support > Bolts > Add Bolts to Surface. Select Bolt 2 under bolt property.
1. This bolt will be assigned to the following material property:
  1. Trend & Plunge: -90º Trend / 20.5º Plunge
  2. Length: 8.5m
  3. Install at Stage: Excavate / Install first bolts
2. Primary path inputs are:
  1. Primary path (required): Start: (14.34 12.17 0.83) and End: (14.34 13.37 0.83)
  2. Primary Spacing (m): 1
  3. Primary Offset (m): 0.5
  4. Secondary Spacing (m): 0
  5. Secondary Offset (m): 0
Press Preview Pattern, then press Done.
To see the installed bolt, select Excavate/Install second bolts stage.
Turn on all the geometry to view the full model by turning on the icons on layers of the geometry in visibility tree.

6.0 Adding Loads

Select the Load workflow tab
Select top-middle surface or Surface load group under Visibility Selection.
Select Loading > Add Loads to Selected.
1. Magnitude = 10 kPa
2. Install at Stage = Add Loads
Select Add Load stage, then you will see the load applied as shown below:

7.0 Restraints

We will now add restrains to the model.

Select the Restraints workflow tab
Make sure only the sides of thin surfaces are selected in the XZ plane or Y Restraint group under Visibility Selection.
Select Restraints > Add Restraint/Displacement > Restrain Y
Then, select the other surfaces in the YZ direction or XY Restraint group under Visibility Selection.
Select Restraints > Add Restraint/Displacement > Restrain XY.
Select the bottom layer (XY Plane) or XYZ Restraint group under Visibility Selection.
Select Restraints > Add Restraint/Displacement > Restrain XYZ.

8.0 Meshing

Select the Mesh workflow tab
Select Mesh > Mesh Settings
Keep the Element type and Mesh Gradation 4-noded tetrahedra and uniform mesh, respectively. Select Medium for Mesh Density.
Click Mesh to generate the mesh, and then OK.
1. The mesh is now generated, your model should look like the one below.

The mesh is now generated, your model should look like the following image:

9.0 Computing Results

Select the Compute workflow tab
From this tab, we can compute the results of our model. Before commencing the stress analysis computation, it is recommended to save the final model as a separate file so that you can access the original file anytime. Select File > Save As.

10.0 Results

Select the Results workflow tab
By default, under Legend, the Results Element type is set as Solids and Sigma 1 Effective Stress as Data Type.
To add a contour plane at the centre of the model, select Interpret > Show Data on Plane > XZ Plane
Keep the setting as default and select Add and Close.
Select Add Load stage and you will see the following Sigma 1 Effective Stress result as shown:

The major principal effective stress distribution is similar to that of RS2.
Select Total Displacement for contour plot.

The maximum displacement contour of RS3 and RS2, are also in alignment, both indicating bulging of the sheet pile wall and the heave of the bottom of the excavation due to removal of the excavated material.

10.1 Liner

The resistance against bulging of the soil by the sheet pile can be shown with Y moment diagram of Liner.

Under Legend, switch the Results Element type from Solids to Liners and select Moment Y for its Data type.

Moment values plotted on RS2 show a good match in both the magnitude and the location of which the maximum moment occurs, as well as its distribution.

10.2 Bolt

The Axial Force induced along the length of the bolt can be shown following the step below:

Under Legend, switch the Results Element type from Liners to Bolts and select Axial Force for its Data type.
Click both Bolt Results Entities and select Interpret > Graph Data...

Exporting this data to Excel, by Right-Click > Plot in Excel, as well as the bolt axial force data from RS2 in Stage = Add Load, the graph shows that the load induced in bolts are well-aligned in both programs.

This concludes the Anchored Sheet Pile Wall Tutorial.

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