deformation in plaxis

[coopernik]

Raising water table in embankment I obtained deformation, like 0.01 m, how it is possible?
what cause deformation in Plaxis?

 

[dgillette]

You'll need to supply a whole lot more information than that, if you want anyone to be able to help. This would include the material constitutive models (is the shear modulus dependent on confining stress?), whether hydrostatic pressures are applied to the surface, in what direction the deformations occurred, how much volumetric strain there is vs amount of shear strain, etc.

Plaxis, FLAC, and the like often show small movements as they adjust to equilibrium with fairly minor changes in boundary conditions. Are you concerned that your model will give bad results, or is this more just intellectual curiousity?

 

[coopernik]

dgillette
my problems comes with misunderstanding of the code. From a my point of view PLAXIS can not be a black box. It is not just a curiosity.

Your answer regarding maintaining equilibrium with minor change in boundary conditions seems to me pretty interesting. Indeed Plaxis can do it in such a way.

Additionally, I´d like to ask for another problem. I ve got two steps of computation. First. I loaded a surface and I obtained a settlement. Second. I take away a loading and I obtained another field of deformation. The answer provided by Plaxis was due to change in B.C.? There is no change in external loading, so why model experienced some deformation in second step? I think its without any physical meaning. Am I correct?

 

[dgillette]

When you raise the water table, wouldn't that cause a decrease in effective normal stress, thereby allowing rebound of compressive strain (and perhaps some softening if the modulus is sensitive to confining stress)? Were the calculated deformations consistent with the reduction in confining stress?