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Finite Element Groundwater Seepage
Phase2 includes steady-state, saturated-unsaturated finite element groundwater seepage analysis built right into the program. There is no need to use a separate groundwater program; the seepage analysis is fully integrated with the stress analysis in Phase2. The pore pressures computed from the groundwater analysis are automatically used in the stress analysis to compute effective stress.
Flow lines and Total Head contours after seepage analysis
Other quantities are also calculated such as flow rate, hydraulic gradient and discharge velocity. The groundwater seepage analysis in Phase2 can be used as a standalone groundwater program, independently of the stress analysis functionality.
Seepage analysis of cofferdam
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Groundwater Seepage: Project Settings
To enable groundwater seepage analysis, set the Groundwater Method = Finite Element Analysis in the Project Settings dialog.
If you are not interested in stress analysis results, you can select Compute = Groundwater Only in Project Settings. Or you can select the Compute (Groundwater) toolbar button.
Project Settings dialog (groundwater seepage option)
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Groundwater Seepage: Boundary Conditions
The hydraulic boundary conditions for finite element groundwater analysis are defined with the Set Boundary Conditions option.
Set Boundary Conditions dialog
Options include:
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Total Head (H)
Zero Pressure (P=0)
Nodal Flow Rate (Q)
Normal Infiltration (q)
Vertical Infiltration (q)
Unknown (P=0 or Q=0)
None / Remove BC
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Just select an option in the dialog, and select the desired boundary segments or nodes. Hydraulic boundary conditions are assigned with just a few mouse clicks. Boundary conditions can also be applied using right-click shortcuts.
Total Head boundary conditions for dam model
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Groundwater Seepage: Hydraulic Conductivity (Permeability)
For a finite element groundwater analysis, you must define the hydraulic conductivity (permeability) for each material. You can define the saturated permeability, anisotropic parameters, and the unsaturated permeability function for each material in the Define Hydraulic Properties dialog.
Define Hydraulic Properties dialog
You may choose from the following permeability models:
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Brooks and Corey
Fredlund and Xing
Gardner
Van Genuchten
Simple
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Built-in data tables are available at the click of a mouse, providing typical input parameters for a variety of material types. References are provided for each data set.
Hydraulic parameters for various materials
The permeability function defined by the current parameters can be displayed by selecting the Plot Function button.
Plot of van Genuchten permeability function
You may also define your own user-defined permeability function (i.e. Matric suction versus Permeability).
User Defined Permeability Function dialog
For multi-stage models, hydraulic parameters can be staged by selecting the Stage Hydraulic Properties checkbox, and selecting the Define Factors button. This allows you to modify the values of the hydraulic parameters at different stages (e.g. to simulate an increase or decrease in permeability with time).
Staged hydraulic properties option
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Groundwater Seepage: Water Table
After a groundwater seepage analysis, Phase2 will display the Water Table which has been determined from the analysis. The Water Table represents an iso-line of zero pore pressure.
Water Table and Pore Pressure contours
The Water Table can be copied to the clipboard or saved to a DXF file, for import into other programs.
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Groundwater Seepage: Discharge Sections
A Discharge Section in Phase2 is a user-defined line segment, through which the steady state, volumetric flow rate of groundwater, normal to the discharge section, will be calculated during a finite element seepage analysis. The value of the flow rate will be displayed in the Phase2 Interpret program, when you view the analysis results.
Volumetric flow rate through Discharge Section (green line segment)
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Groundwater Seepage: Flow Lines
A flow line represents a path of fluid flow through the material. Flow occurs in the direction of decreasing Total Head. For a material with isotropic permeability, flow lines are perpendicular to contours of Total Head. Flow lines can be added individually to a model, with the Add Flow Line option, or multiple flow lines can be simultaneously generated with the Add Multiple Flow Lines option.
Multiple Flow lines over Total Head contours
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Groundwater Seepage: Flow Vectors
The Flow Vectors option will display the groundwater flow velocity vectors at each node of the mesh. The Flow Vectors indicate the direction of groundwater flow, and the relative size of the Flow Vectors indicates the relative velocity of the groundwater flow.
Flow Vectors and Total Discharge Velocity contours
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