Problem in Pore Presure Ratio

[subrata]

Hi,
I am performing dynamic analysis of a rectangular (150 m long and 100 m height) soil strata using PressureDependentMultiYield material with “fluidsolidporus” material. I have applied equalDOF constraints at the two lateral boundaries. Dynamic analysis is performed (under undrained condition) after the gravity analysis. If I apply acceleration at the base of the model, pore pressure ratio in soil increases gradually from zero to 1.

However, when I am using horizontal dampers at the two lateral boundaries (to model radiation damping) pore pressure ratio exceeds 1 and goes upto 5. Moreover, in this case pore pressure ratio crosses the value 1 even before liquefaction occurs (that can be found from confinement pressure vs shear stress diagram). In some cases, soil elements are not liquefying but the values of pore pressure ratio reaches 1.

Can anybody tell me why I am not getting correct pore pressure ratio?

Thanks in advance,
Subrata

[cyz1654]

hello,subrata,I want to study from you .I want to know how to know whether soil liqueafy or not and how to record pore pressure ratio ?
My email is cyz1654@hotmail.com.