Ushnish Basu
Ansys Employee


I will give the following general  tip that typically, pore-pressure problems use LOAD_BODY and INITIAL_STRESS_DEPTH to include the effect of gravity. 

You can search for the following paper online "Modelling liquefaction of soils with LS-DYNA using a SANISAND-based material model", as it has some discussion of modeling pore-water-pressure problems.

Also, please be sure to read through the Remarks under CONTROL_PORE_FLUID and INITIAL_STRESS_DEPTH in the latest versions of the manual