Phase2 Model > Groundwater
The primary purpose of the groundwater options in Phase2 is for the determination of pore pressures which can be incorporated into the stress analysis to compute values of effective stress. Furthermore, if you choose the finite element seepage analysis option, a steady-state seepage analysis can be carried out to compute pore pressures as well as flow rates and other hydraulic quantities.
To model groundwater in Phase2:
First select the desired Groundwater Method in the Project Settings dialog. There are 3 possible methods which are available:
Use the applicable options (see below for details) to define the groundwater conditions for your model.
Piezometric Lines
If the Groundwater Method = Piezometric Lines:
Piezometric Lines are created with the Add Piezometric Line option in the Boundaries menu.
After they are created, Piezometric Lines are assigned to the desired materials, and the staging sequence can be defined, with the Define Hydraulic Properties option in the Properties menu.
If your piezo lines are staged, you can view only the piezo line(s) applicable to the current stage, with the View Piezos by Stage option in the Groundwater menu.
Water Pressure Grid
If the Groundwater Method = Water Pressure Grid:
The Water Pressure Grid is defined with the Water Pressure Grid option in the Groundwater menu.
The Water Pressure grid can be assigned (or turned off) for each material with the Define Hydraulic Properties option.
Finite Element (Seepage) Analysis
If the Groundwater Method = Finite Element Analysis:
The hydraulic boundary conditions are defined with the Set Boundary Conditions option in the Groundwater menu.
The hydraulic material properties are defined with the Define Hydraulic Properties option in the Groundwater menu.
Optional - if you wish to compute the steady-state flow volume across a line segment, use the Add Discharge Section option in the Groundwater menu to define a discharge section.
Optional - if you wish to compute the seepage analysis only (without computing the stress analysis), then you can use the Compute (groundwater only) option. This allows you to view and verify the seepage analysis results, before proceeding to the effective stress analysis.
With the finite element seepage analysis option, the seepage analysis can be used to calculate pore pressures for an effective stress analysis, just as with the Piezometric Lines or Water Pressure Grid options. It can also be used as a standalone option, independently of the stress analysis in Phase2 (i.e. you can run a seepage analysis without necessarily computing a stress analysis).
This allows Phase2 to be used as a steady-state, finite element seepage analysis program, for complex multi-stage problems. Flow rates, hydraulic gradients and other quantities can be computed, in addition to pore pressure.