Water Pressure Grid

The Water Pressure Grid option allows you to model the groundwater pore pressure distribution by defining the total head, pressure head or pore pressure at a grid of discrete x,y locations. From the data at the grid points, the pore pressure at any point in the ground is determined using the specified interpolation method.

The grid data could be based on field measurements or could be the output from a seepage analysis program (such as the finite element seepage analysis which is available within RS2 ).

The Water Pressure Grid option is found in the Analysis menu. There are three Grid Type options:

• Pore Pressure
• Total Head
• Pressure Head

To define the Water Pressure Grid:

1. In the Joint Properties tab of the Input Data dialog, change the Water Pressure = Water Pressure Grid. Select OK.
2. Select Analysis > Water Pressure Grid , and you will see the Water Pressure Grid dialog.
3. Set the desired Water Pressure Grid type (Total Head, Pressure Head, or Pore Pressure) from the drop-down list at the top of the Water Pressure Grid dialog.
4. Set the desired interpolation type from the second drop-down menu at the top of the Water Pressure Grid dialog.
5. You can type or paste data into the spreadsheet at the right of the dialog, or you can import data into the spreadsheet by selecting the Import button (see below for details). Each grid point is defined by x and y coordinates, and a value, corresponding to the Water Pressure Grid type (Total Head, Pressure Head, or Pore Pressure) selected in the drop-down menu at the top of the dialog.
6. When finished entering or editing data, select OK.
7. The location of each grid point will be marked by a blue triangle on the Opening Section view. Grid values can be displayed at each grid point with the Display Options dialog. By default, they are NOT displayed.

Importing Water Pressure Grid Files

The Import button in the Water Pressure Grid dialog allows you to import water pressure grid data from a file into the current UnWedge model. The following file formats can be imported:

• .PWP files: A .PWP file is a space-delimited text file, where each row of the file has the format ( x y value). The type of the value must correspond to the Grid Type (Total Head, Pressure Head or Pore Pressure)
• Text files: You can import water pressure grid data from comma, tab or space-delimited text files, with .CSV, .PRN or .TXT extensions. Each row of the file must be in the format (xy value), where the data is separated by the appropriate delimiter.
• .FEZ files (RS2 Groundwater Analysis file): If you have performed a finite element groundwater analysis with RS2, then the results can be imported into UnWedge as a water pressure grid file. The data will be imported in the form of either Total Head, Pressure Head, or Pore Pressure, according to the selection of the Grid Type.

Exporting Water Pressure Grid Files

The Export button in the Water Pressure Grid dialog allows you to export the current data in the Water Pressure Grid dialog, to a .PWP file (see above for the definition of a .PWP file). This is useful if you wish to later import the same Water Pressure Grid into another UnWedge model.

Display of Water Pressure Grid

The location of each grid point is marked by a blue triangle on the model. By default, the values at the grid points are NOT displayed. If you wish to display the water pressure grid values, select the Show Grid Values checkbox in the 2D Views tab of the Display Options dialog.