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; or the slope stability program Slide2, also available from Rocscience).

NOTE: Multiple water pressure grids can be defined, to allow staging of grid values or to use different grids for different materials.

The Water Pressure Grid option allows users to select from three grid types:

• Total Head
• Pressure Head
• Pore Pressure

To define the Water Pressure Grid(s):

1. Select Water Pressure Grid from the Groundwater menu, and you will see the Water Pressure Grid dialog.
2. Select a Water Pressure Grid Type from the drop-down menu in the Water Pressure Grid dialog.
3. By default, one (blank) grid is initially defined. 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.
4. Multiple Grids - if you require more than one grid, select the Add button to create the desired number of grids. A list of default grid names will appear. You can customize the name for each grid (e.g. Stage 1, Stage 2 ...) by clicking on the grid name and selecting the Rename button. To enter data for each grid, click on the grid name and enter the data as described in Step 3.
5. When finished entering or editing data select [OK].
6. The location of each grid point will be marked by a blue triangle on the model. Grid values can be displayed at each grid point with the Display Options dialog. By default, they are NOT displayed.

NOTE: after you have defined water pressure grid(s), the staging and/or material assignment of the grid(s) is specified in the Define Hydraulic Properties dialog.

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 RS2 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 Groundwater Method in Project Settings (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 (x y value), where the data is separated by the appropriate delimiter.
• .SLW files (Slide2 Groundwater Analysis file) – if you have performed a finite element groundwater analysis with Slide (slope stability program from Rocscience), then the results can be imported into RS2 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 Groundwater Method in Project Settings.

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 RS2 model.

Assignment of Water Pressure Grid

If only a single water pressure grid is defined, it is automatically assigned to all materials for all stages. If multiple water pressure grids are defined, then you must use the Define Hydraulic Properties dialog to specify the staging and/or material assignment of the grids, for each material.

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 check box in the Display Options dialog.