Problem description

For phases that do not have their own pore pressure settings, but take the pore pressures from the previous phase (i.e. pore pressure calculation type “Use pressures from previous phase“), the water pressures and -settings are not updated in the data files once the water pressures and water settings are generated for these phases with the “Use pressures from previous phase“-option.

Typical calculation types where this occurs are:

• Safety analysis
• Consolidation analysis by means of a minimum excess pore pressure or degree of consolidation

It will lead to incorrect pore pressure settings in for example these scenarios:

• a safety phase and its previous phase were already calculated, and in the previous phase the water pressures were changed. Now when launching the calculation, the water pressures for the previous phase are updated (e.g. a different water level), but not for the safety phase: here it will take the water pressures as defined in the earlier calculation
• a safety phase and its previous phase were defined and for both the preview was inspected. Prior to calculation, the water pressure settings for the previous phase were changed.
• a consolidation phase with minimum excess pore pressure and its previous phase were defined and only for the consolidation phase the preview was inspected. Prior to calculation, the water pressure settings for the previous phase were changed.

It is not a problem when:

• the mesh is regenerated. Now all water pressures will need to be regenerated for all phases, including the types Safety, Consolidation by Minimum Excess pore pressures and Consolidation by Degree of Consolidation.

Solution

This issue has been fixed since PLAXIS 3D 2013.01

For older versions (3D2013.0), a manual workaround is available: use

__writephasestomesh SomePhase True

With SomePhase is the object name of the phase that uses the “Use pressures from previous phase”-option (Phase_2, Phase_3, etc)

Advanced workaround

With the set of commands below, it is possible to do this in one go via the Expert > Commands Runner option for any configuration of phases:

groupfiltered Phases "ShouldCalculate=True"
groupfiltered groups[-1] "PorePresCalctype=Use pressures from previous phase"
__writephasestomesh groups[-1] True
ungroup groups[-1]
ungroup groups[-1]

Even more convenient would be to assign this to a Macro (see also the Expert menu), so it can be called via the Expert menu with a single click.