Hello dear sirs...
When I model soil with high OCR by modified cam clay model in Plaxis 2D, no softening behavior is predicted by the model and it is not true!!!
this result is similar in the soil test module (one element model) and the simulation of the triaxial test is FEM environment. If a similar specification of soil is modeled in Plaxis 3D (soil test module) the result is correct and softening behavior will be predicted.
please check the picture which I captured from Plaxis 2D
Picture Link
Hello Sajjad,For softening behavior of soils with high OCR, you may consider OC Clay constitutive model shown in the link below:communities.bentley.com/.../oc-clay---plaxis-udsm
Answer Verified By: sajjad shakeri
Hi dear Hung,
1. Modified cam clay can predict the softening behavior of clays.
2. The main problem is that the MCC model in Plaxis3D (soil test modulus) predict the soil behavior but for the same parameter the result is completely different in Plaxis2D soil test.
Hi,
1) Theoretically yes, in practical finite element analysis it cannot due to the mesh dependency of softening behaviour.
2) The main problem is that MCC is unsuitable for modelling softening due to 1). And in SoilTest there is actually no mesh, it's based on a single stress point which means the program has to pick an arbitrary shear band with for softening. I can imagine that is done differently in 2D and 3D Soiltest. But again, it 's better to use OC Clay as my colleague Hung already suggested, so overcome these problems.
With kind regards,
Dennis Waterman