A Longitudinal Deformation Profile (LDP) is a plot of the tunnel wall convergence along the length of the tunnel (i.e. convergence versus the distance from the tunnel face). The LDP is used in RocSupport when the method of Support Installation = Distance from Tunnel Face. The LDP function is used to convert the Distance from Tunnel Face into a value of Tunnel Convergence at the point of support installation.
By default, RocSupport will use a built-in LDP function - see the Support Installation topic for an illustration of the default LDP function. When the default function is used, it is not necessary for the user to specify the function, the analysis will automatically use this function.
If you do not wish to use the default LDP function, then you can easily select or define your own LDP function, as described below.
User Defined Longitudinal Deformation Profile
To select or define your own LDP function:
In the Support Parameters dialog, set the method of Support Installation = Distance from Tunnel Face.
Select the Advanced button (beside the Distance from Tunnel Face option).
You will see the Longitudinal Deformation Profile dialog.
In this dialog, you can select, edit or define new LDP functions, as follows.
The drop-list in the dialog will list all currently defined LDP functions.
If there are no current user-defined functions, then only the Built-In Function (i.e. the default LDP function) will be listed in the drop-list. Note: you can view a plot of the Built-In Function by selecting the View button.
New - to define a new LDP function select the New button. This will open another dialog, in which you can define a new LDP function. See below for details.
Edit - To edit a user-defined LDP function, select the function name from the drop-list, and select the Edit button. This will open another dialog, in which you can edit the LDP function. See below for details.
Delete - to delete a user-defined LDP function, select the function name from the drop list, and select the Delete button. The function will be deleted from the list. Note: you cannot delete the Built-In Function.
Import - to import LDP functions from other RocSupport files, select the Import button, and open an existing RocSupport file.
If you have existing user-defined LDP functions, then you can select a user-defined function name from the drop-list. To use the currently selected LDP function in the analysis, select OK. This will return you to the Support Parameters dialog, and the selected function will be used in the analysis.
Defining a New LDP Function
To create a New LDP Function:
Select the New button in the Longitudinal Deformation Profile dialog (see above).
This will display the User Defined Longitudinal Deformation Profile dialog.
Enter a Name for the function.
Define the function by entering values in the grid. NOTE:
The X-axis of the function (Distance / Radius) is the distance along the tunnel, divided by the tunnel radius. These values will (in general) begin with negative values, because the starting value of distance is "ahead" of the tunnel face. Zero represents the position of the tunnel face, and positive values represent distance behind the tunnel face (i.e. the excavated part of the tunnel).
The Y-axis of the function (Scaled Displacement) is the normalized wall displacement. All displacements are divided by the maximum tunnel wall displacement. Therefore the values will range between 0 and 1.
As you enter data in the grid, the function will automatically be plotted in the graphing area at the right of the dialog. Note: on the graph the data points can be graphically edited, if desired, by clicking on them and dragging them with the mouse.
When all values have been entered, select OK to return to the Longitudinal Deformation Profile dialog.
The Name of the new function will appear in the drop-list in the Longitudinal Deformation Profile dialog. Select OK to return to the Support Parameters dialog.
TIP: you can use the Built-In LDP function as a starting point for creating a new LDP function, by selecting the Create Default button in the User Defined Longitudinal Deformation Profile dialog. This will automatically fill the grid with the data points which define the Built-In function. You can then edit these points to create a new function. You may find this a useful shortcut.
Editing an LDP Function
To edit an existing user-defined LDP Function:
Select the function name in the Longitudinal Deformation Profile dialog.
Select the Edit button.
This will display the User Defined Longitudinal Deformation Profile dialog, in which you can edit the function as required.