Free Field Analysis

[maryammf]

Dear all,

I decided to do the free field analysis by using the same material that was used for analysis of a saturated soil element under harmonic motion in an opensees example. So, I used nDMaterial PressureDependMultiYield and nDMaterial FluidSolidPorous together to capture the undrained condition. I used the rollers for the side boundaries (horizontally constrained) and the same at the base (vertically constrained) and applied a harmonic load at the base in form of acceleration; exactly the same procedure for the saturated soil element under harmonic load as the opensees example just I am using for a group of elements instead of one! But the result for excess pwp is strange and is harmonic instead of blowing up! I do not know where I am doing wrong! I will appreciate your suggestions in this respect.

Bests,
Maryam

[jaimercado]

Maryam

What kind of element are you using? Quad, 94Quad...? For the Quad, first, remember to use buoyant unit weight of the soil when using FluidSolidPorous. Second, check the bulk modulus you are using. If you are using 94Quad, the FluidSolidPorous is not necessary since you can fix the 3 dof at water table depth to ensure that the pore pressure is zero.

Post your code to help you in a better way.

[maryammf]

Hi,

Thanks for your msg. It is solved as there was a problem in b.c. definition.