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Ask for a constitutive model for soil with dilantancy and hardening

Dear researchers,

My name is Chi and I just started my PhD study two months ago. I am experimentally and numerically studying the pore pressure build-up in sands during the pile load test and hence, at the first stage, I need to have a constitutive model for soil with both dilatancy and hardening behaviors.

Due to the practical feasibility, I tend to search or build a model developed from Mohr-Coulomb model for soil with only several parameters which can be determined from the conventionl laboratory tests. I heard about some models as Advanced Mohr-Coulomb or Modified Mohr-Coulomb which exit on some commercial software as PLAXIS, DIANA, ABAQUS... However my final goal will be the coupled dynamics-consolidation problem related to pile load test therefore I wish to have a source code of one model and then developed it further.

If any one of you knows about any open-source code for such a constitutive model (Advanced Mohr-Coloumb for soil with both dilatancy and hardening behaviors), could you please tell mehow/where I can find it?

Thank you so much for your help and your time,

Best regards,




From what I have read from your post, I think you only need to change the constitutive model of granular materials. Basically, it does not matter whether you are using commercial or open-source FE codes. You only need to search FE code which provides an interface for user material routine. For instance, ABAQUS has a nice UMAT interface, and also FEAP.

BTW, for representing both dilatancy and hardening behaviours, the modified Drucker-Prager model with Cap will be also an option. Time-depedent behaviour is also available in the model implementation in ABAQUS.


Dear Gan,

Thanks for your reply with a good idea about using UMAT routine. I still have some problems which I should clarify from the begining:

1) The final goal of my research will be a problem of coupled dynamics-consolidation analysis since I am dealing with a pile load test in saturated sand, I need to know both the stress-strain states of and the pore pressure in the soil mass. And as I understand (maybe I am wrong), there is no commerical software can perform this coupled dynamics-consolidation analysis.

2) Since I also conduct physical modeling, I preferto use a simple constitutive model with not-too-much parameters which can be determined from the conventional laboratory tests and Advanced/Modified Mohr-Coulomb is what I thought about first.

One more time, thanks for your reply.


alishafi's picture

Dear gan

Im Ali. I faced your problem as well. The best model for your research is Subloading tij model. also if you want to make a dynamic model using ABAQUS/Explicit, you must use VUMAT interface for producing your model.

With regards


alishafi's picture


I'm Msc Student of geotechnical engineering. Im looking for an appropriate model for sands in order to produce a dynamic model for sand compaction piles for estimating the effective radius of them. I have read a Modified Druker prager /cap model but its parameters has modified for a special use of dynamic compaction method by considering the depth effects. In my model, because I am using the plane starin condition, the most important thing is which model can consider the cylindrical expansion of sand compaction piles. I have also read the  SUBLOADING Tij model. Now I don't know which model is better. Please help me by your precious suggestions.

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