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How to reach ctitical state in a triaxial compression test?

Asked by Leonard

Hi everyone,

I'd like to ask you the help on any possible suggestions to make a sand sample reach the critical state (no volumetric strain occurs) in triaxial compression test.

I use cohFrictMat (with rolling resistance) and CohesionMoment for the simulation, the boundary condition is six rigid walls. And I have been testing a lot on calibrating the parameters of my model, but I still can't get a result which can reach the critical state, even at larger strain level, as a typical result of my tests in [1].

Refer to papers such as [2] and [3], it is very nice that the critical state has been captured. I guess I miss some knowledge on capturing this behaviour. I feel that the occurrence of critical state could be affected by many factors (not sure). I'd like to ask your valuable suggestions on this issue. For example, does the occurrence of this state only depend on the contact parameters? Is it related to the strain rate? Any efficient way to get this state?

Thanks very much!
Leonard

[1]https://we.tl/t-tQUUETv2L5

[2]Hosn, R. A., Sibille, L., Benahmed, N., & Chareyre, B. (2017). Discrete numerical modeling of loose soil with spherical particles and interparticle rolling friction. Granular matter, 19(1), 4.

[3]Plassiard, Jean-Patrick, Noura Belheine, and Frédéric-Victor Donzé. "A spherical discrete element model: calibration procedure and incremental response." Granular Matter 11.5 (2009): 293-306.

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Jérôme Duriez (jduriez) said : 		#1

Hi,

Outside proposing to shear more (which axial strain did you actually reach ?), I would expect your DEM model to suffer from some biais affecting the simulated rheology, if that one is not the one of granular soils.

Even though this answer probably does not help, maybe it s a motivation to check what are the parameters of DEM simulations that influence DEM results. ;-)

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Leonard (z2521899293) said : 		#2

Hi Jérôme,
>which axial strain did you actually reach ?
 I sheared to 40% of strain, typical results could be found in [1] if you are interested

>>Could you please give some suggestions on which biais that could affect the simulated rheology? Did you mean the model parameters such as contact friction angle, rolling resistance, rolling limit coefficient?

>>check what are the parameters of DEM simulations that influence DEM results.
Yes, this is what I am doing now!

Thanks
Leonard
[1]https://we.tl/t-NngdRx33jQ

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Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Open' state without activity for the last 15 days.