RE: Consolidation analysis

Vasileios Basas — Fri, 10 Feb 2023 14:33:39 GMT

Hi Aurélien,

When running a Consolidation analysis with a Staged Construction loading type, it is necessary to specify a value for the Time interval parameter, which has, in this case, the meaning of the total consolidation period applied in the current calculation phase.

Although the time interval of each phase adds up to the previous total Time, this is only reflected in graphs where you plot a quantity (e.g. settlements or excess pore pressures) against the Time. This idea is logical because it would only be possible to express these quantities' development throughout staged construction (Time).

Regarding your first question, you can extract data from those graphs and post-process them in a spreadsheet, thus being able to plot them in different time intervals. Alternatively, you could select the "Reset time" option from the "Deformation control parameters" of each calculation phase, which will reset the history curves where Time is used on one of the axes.

Regarding your second question, it would be prudent to ask the person who gave those suggestions, as they may have a better idea and understanding of your model. However, given the limited information that I have at my disposal, I can explain a couple of things:

The "Ignore undrained behaviour" option temporarily excludes the effects of undrained behaviour in situations where undrained material data sets (Undrained (A) or Undrained (B)) are used. The selection of this option is associated with the selection of the Plastic calculation type. When the option is selected, the water's stiffness is not considered. As a result, all undrained material clusters become temporarily drained. Existing excess pore pressures that were previously generated will remain, but no new excess pore pressures will be generated in that particular calculation phase. This option is usually essential to ensure that Gravity loading results in initial effective stresses when undrained materials are used.
On the other hand, the "Reset displacements to zero" option should be selected when irrelevant displacements of previous calculation steps are to be disregarded at the beginning of the current calculation phase so that the new calculation starts from a zero displacement field. For example, deformations due to gravity loading are physically meaningless. Selecting this option is unnecessary because you can check your phase displacements instead of total displacements. However, if the deformations of Phases 3 and 4 are irrelevant to your analysis, then you can select it.

I hope this clarifies things a bit.