Advanced Groundwater
On the Groundwater page of the Project Settings dialog, the following advanced groundwater options can be enabled:
- Transient Groundwater
- Excess Pore Pressure
- Rapid Drawdown
To enable one of the advanced groundwater options, select the Advanced checkbox and choose an option. Only ONE option can be selected, it is not possible to run more than one advanced groundwater option simultaneously. The advanced groundwater options are summarized below.
Transient Groundwater
The Transient Groundwater option allows you to carry out transient (time-dependent) finite element groundwater seepage analysis. You can define multiple stages at different times with changing groundwater boundary conditions at each stage. To carry out a transient groundwater analysis:
- Select the Transient Groundwater option on the Groundwater page of Project Settings.
- Select the Transient page in Project Settings, and define the number of stages and times. See the Transient Groundwater topic for details.
- You will then be able to define groundwater boundary conditions at each time stage and carry out a slope stability analysis at any or all stages.
See the Slide2 Tutorials for detailed tutorials describing how to set up a transient groundwater model.
Excess Pore Pressure
The Excess Pore Pressure option allows you to use the B-bar method to calculate excess pore pressure due to undrained loading. The B-bar method allows you to account for sudden increases in pore pressure due to rapidly applied loading conditions. These loading conditions may include:
- added material weight
- vertical seismic loading
- vertical external loading
When you select the Excess Pore Pressure option, you will be able to define B-bar coefficients for materials in the Define Material Properties dialog. Excess pore pressure is equal to the B-bar coefficient multiplied by the change in vertical stress. The change in vertical stress can be due to any of the above loading conditions. See the Excess Pore Pressure topic for more information.
Rapid Drawdown Analysis
The Rapid Drawdown option allows you to analyze the stability of earth dams under rapid drawdown conditions, using one of four methods:
- Duncan, Wright, Wong, 3 stage (1990)
- Army Corps of Engineers, 2 stage (1970)
- Lowe and Karafiath (1960)
- Effective Stress using B-bar
For all methods, an initial water level is specified by defining a Water Table. A second water table defining the drawdown level can also be specified, or you can assume a complete drawdown. The pore pressure is then calculated according to the drawdown method, and the safety factor for rapid drawdown conditions is calculated. For tutorials that demonstrate these options, see the Slide2 Tutorials page.