Dear All,
I hope someone can give me some advice on the following issue that I have with Abaqus:
I am trying to model a laterally loaded pile in clay under undrained condition using Cam-Clay model. In my model I have ground water which is 4 meters above the ground surface, for modelling the water, I have applied Pore-Pressure boundary condition and calculated the magnitude of it as (Depth of the water x the unit weight of the water ) I am not sure if this is the right way to take account of the surface water in Abaqus if so , does the direction has be negative (downward) or positive (upward) please. I really appreciate your comments. Thank you in advance.
Hi Hemn,
Both your method and the magnitude of the pore pressure (PP) seem correct. The direction is not relevant as pressure is omnidirectional/hydrostatic, i.e. it has the same magnitude in all directions. However, the sign is relevant as you say and for you I feel it should be positive at the soil surface.
Other readers please correct me if I am wrong, but PP would only be negative at (or below) the soil surface if you had a three-phase interface, e.g. soil+water+air or porous rock+water+overlying immiscible organic liquid like low-density oil. Then you would have capillary action effects as the water would be more 'wetting' than the other fluid. I use such a condition in a prior paper when I have an evolving free surface:
https://dx.doi.org/10.1002/nme.2040
Anyway - hope this helps,
Milan.
Hi Hemn,
Just checking in to see if this all worked out for you.
Best,
Milan.
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