Tutorial 19 - Embankment Cross Section Designer

This tutorial introduces the Cross Section feature in the Embankment Designer dialog in Settle3 that allows users to define layers within the cross section of an embankment. This will enable the user to build the embankment in any predefined layering which simulates road, dam construction or extension of old embankments.

By the end of this tutorial you should know how the Stone Columns feature works, what parameters are required to implement it, and how to model it in an embankment in different stages.

Topics Covered in this Tutorial:

Finished Product:

The finished product of this tutorial can be found in the embankment_final.s3z file. All tutorial files installed with Settle3 can be accessed by selecting File > Recent Folders > Tutorials Folder from the Settle3 main menu.

1.0 Introduction


The Embankment Cross Section Designer feature is closely related to the embankment designer feature which was first introduced in Tutorial 8 which can be found here in the Settle3 tutorials page. To guide users through this new feature, we will model the extension of a road embankment by considering three separate stages. The first stage will represent the existing condition of the road embankment, the second stage will aim to extend the embankment to make the existing road wider, and the third stage will raise the embankment to the appropriate height.

In addition to the soil properties of the subsurface materials and embankment fills, three boreholes will be used to define non-horizontal soil layering. We will now begin by defining the project settings.

2.0 Model


If you have not already done so, run the Settle3 program by double-clicking the Settle3 icon in your installation folder or by selecting Programs > Rocscience > Settle3 > Settle3 in the Windows Start menu.

When the program starts, a default model is automatically created. If you do not see a new model on your screen:

New file icon Select: File > New

2.1 Project Settings

Select: Analysis > Project Settings

In the General Tab, please select the following options:

Project settings dialog

Suppose the embankment is an extension and we are to raise an old road embankment. The following layers are expected to be constructed.

cross section layering image

As shown in the figure above, we need to define three stages of construction in our model. Under the General tab, select Stages. Increase the Number of Stages to 3. Since we are only interested in the immediate settlement, there is no need to check the time dependent calculation box and no need to add time durations for the stages.

Project Setting dialog

Since our model requires non-horizontal layering, select the Soils Profile tab and change the Layer Options to Non Horizontal Layers to allow more than one bore hole to be applied.

Project settings dialog

You can choose the method of interpolation for the extension of layers between the boreholes; for the purpose of this tutorial we will keep the default option of Linear.

Note that this embankment feature does not support non-horizontal ground surfaces. In other words, if the ground surface is non-horizontal the embankment will still be added with a flat surface as the bottom.

Select the Groundwater tab, and select Groundwater Analysis with the Piezometric Line as the method.

Select OK.

2.2 Soil Properties

Soil Properties icon Select: Soils > Soil Properties

Enter the following properties shown in the table below for the two soil layers:

Soil Name

Unit Weight [kN/m3]

Saturated Unit Weight [kN/m3]

K0

Immediate Settlement

Primary Consolidation

Es [kPa]

Esur [kPa]

Material Type

Cc

Cr

e0

OCR

Loose Sand

14

18.53

0.55

10000

10000

 

Soft Clay

18

20

0.3

20000

20000

Non-Linear

0.4

0.04

1

1

Very Dense Sand

21

21

1

80000

80000

 

Bed Rock

18

18

1

 

Make sure to uncheck the Secondary Consolidation Settlement option for every soil layers. In addition, the Bed Rock layer will not undergo any settlement so we will uncheck both Immediate Settlement and Primary Consolidation.

2.3 Boreholes

Now we will define the soil layers by adding three boreholes.

Add borehole icon  Select: Soils > Boreholes > Add Borehole

In the Edit Borehole dialog, input the following values for the corresponding borehole:

Borehole 1

Borehole 1 dialog

Borehole 2

Borehole 2 dialogue

Borehole 3

Borehole 3 dialog

It is worth to notice that boreholes have different depths for every layer. The clay layer is thicker in Borehole 2, which makes the consolidation and overall settlement surrounding this borehole greater than the rest of embankment area. You may also define the soil layers using top and bottom elevation points by unchecking Define Layers by Thickness and inputting the associated elevations.

2.4 Groundwater

Add piezometric line icon Select: Groundwater > Add Piezometric Line

Enter a depth of 2.0 m and select OK to save and close the dialog.

Add piezometric line dialog

Once the Assign Piezometric Line to Soil dialog appears, click Select All and select OK.

2.5 Embankment Cross Section

Select the Embankment Load button located in the toolbar or by following:

Add embankment icon Select: Loads > Add Embankment (Cross Section)

The Embankment Cross Section Designer dialog allows the users to enter the embankment cross section layers and their respective stages. The coordinates may be filled in directly using the coordinates table or may be plotted using the mouse in the plan view.

Embankment cross section designer

To add layers, select the Add button located below the Section Properties field. Using the coordinates from Figure 1, enter the following information

Layer

Stage

Unit Weight [kN/m3]

Vertex

X'

Y'

1

Stage 1

17.5

1

0

0

2

22.5

0

3

16.5

3

4

6

3

2

Stage 2

18

1

6

3

2

16.5

3

3

22.5

0

4

37

0

5

29

4

6

8

4

3

Stage 3

18

1

8

4

2

29

4

3

37

0

4

41

0

5

29

6

6

12

6

After inputting the above information, your embankment cross section should look like the following:

Embankment cross section designer

Once you have input all of the information shown above, select OK to input the coordinates of the embankment's bottom surface.

Enter the following four points: {56,150},{56,50}

Your plan view should automatically update with a rectangular object as shown below:

The three stages will appear as tabs at the bottom of the drawing. Right-click on Stage1 to choose it as a reference stage as the settlement of the stage is already finished and is not required for the new layers added in the road extension.

Set as  Reference stage image

3.0 Computation


3.1 Add Field Points Grid

For this tutorial we will select the Add Field Point Grid option. Choose the number of grid points desired. 400 field points are sufficient for this model.

Select OK and you will be prompted to enter coordinates as we did for the Embankment Designer. For the Field Point Grid you can either enter coordinates or use the plan view; we will just click and drag to cover an area slightly larger than the embankment itself. For reference, see below for sizing of the field point grid.

3.2 Add Query Line

To calculate the overall settlement at each stage a query line is chosen in each direction as shown in the layout above by clicking on “Add Query Line”.

Add query line icon Select: Query > Add Query Line

The query line chosen crossing is at around {35,100}. The settlements are calculated immediately when the query lines appear. If contours of the settlement are required, an area for grid points may be added using the Auto Field Points Grid icon or the Add Field Points Grid icon.

 

4.0 Results


The settlement contours and values for the query line will be immediately calculated and shown. You may see the settlement of each stage by clicking through the stage tab at the bottom.

Final figure

As expected, the maximum settlement occurs in the region closest to Borehole 2.

You can refer to other tutorials to learn how to handle other options for time dependence.

This concludes the Embankment Cross Section Designer tutorial. You may now exit the program.