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[Luc Scholtès <question658902@xxxxxxxxxxxxxxxxxxxxx>]

Question #658902 on Yade changed:
https://answers.launchpad.net/yade/+question/658902

    Status: Open => Answered

Luc Scholtès proposed the following answer:
Hello,

Here are some answers:

1) and 2):

calibration of DEM models is a difficult task if you want it to be
relevant. Many DEM/BPM users often underestimate the calibration process
which has to be done considering as much loading paths as possible:

- uniaxial tension test -> elastic properties and uniaxial tensile strength (some people might want to simulate brazilian tests so as to compare directly with lab experiments)
- uniaxial compression test -> elastic properties (must be the same as in uniaxial tension) and uniaxial compressive strength
- triaxial compression tests at several confining pressure -> failure envelope

Please have a look at [1] where a calibration procedure is explained (I
insist on the fact that this is A calibration procedure and not THE
calibration procedure). Also, you will see in that paper that every
microproperty of the JCFPM are related to given macroscopic properties.
Of course, as usual for DEM model, it is a matter of trials and errors
to identify the right set of microproperties. There is no direct
mathematical relationship between micro and macro properties (unless you
work with regular packings...).

3) I don't remember performing a biaxial test for that paper... I
remember performing a uniaxial compressive test on a sample with a pre-
existing crack and a direct shear test on a sample with several pre-
existing cracks. I guess you are referring to the direct shear test. The
procedure is exactly the same that you would use in the lab: normal
loading through top moving plate and bottom fixed plate and then, after
reaching the desired normal load, shearing with the help of lateral
walls (Casagrande box type). Please have a look at this thread:

https://www.mail-archive.com/yade-
users@xxxxxxxxxxxxxxxxxxx/msg05815.html

Luc

- [1]: Scholtès, L., Donzé, F.V. (2013), A DEM model for soft and hard
rocks: role of grain interlocking on strength. Journal of the Mechanics
and Physics of Solids (61), pages 352–369.

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