Yade

Triaxial strength and strain about JCFpmMat parameters

Asked by Ziyu Wang on 2022-02-21

Hello,everyone.
I try to use JCFpmMat to simulate rock materials,but there are many parameters in JCFpmMat such as young,poisson,tensileStrength,cohesion,frictionAngle..

I don't know which parameters are related to the peak strength of the material,I made a series of attempts, but the simulation was a little time-consuming and failed to draw a certain rule.(in my triaxial compression simulation, I set that when the stress is lower than 90% of the historical maximum stress, it is regarded as sample failure)

So,I wonder if anyone has done similar work and can give some suggestions about parameters. At present, the peak strength I get is lower than my requirements. How should I adjust the parameters?

Best wishes!

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Language:: English Edit question

Status:: Solved

For:: Yade Edit question

Assignee:: No assignee Edit question

Solved by:: Jérôme Duriez

Solved:: 2022-03-04

Last query:: 2022-03-04

Last reply:: 2022-03-03

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Luc Scholtès (luc) said on 2022-02-22:

Hello,

I copy here a citation from reference [1] where the calibration procedure of the JCFPM model is explained:

"... the calibration procedure was run as follow:
1. Choice of a coordination number N allowing matching the desired tensile strength to compressive strength ratio sigmac/sigmat. As a first approximation, from the authors’ experience the c/t ratio is taken equal to the macroscopic sigmac/sigmat ratio. Looking
first arbitrary, this option seems however to capture the micromechanisms usually observed experimentally as tensile cracking is representative of the brittleness of the material.
2. Determination of the elastic parameters Eeq and kn/ks in order to match the elastic properties (Young modulus and Poisson ratio) by running either tensile or compression tests.
3. Determination of the local tensile strength t in order to match the tensile strength sigmatof the material by running tensile tests.
4. Determination of the interparticle friction angle in order to match the slope of the failure envelope by running a series of triaxial compression tests at different confining pressures."

Of course, the citation makes sense only if you have a look at the model description in the same paper and at the discussion about the N value (coordination number/number of bonds per particle which is a function of the interaction radius defining near neighbour interactions).

For sets of values for a granite or a sandstone, you can have a look at table 3 of the same article.

Do not hesitate if you have other questions.

Luc

[1]: https://www.sciencedirect.com/science/article/abs/pii/S0022509612002268

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Ziyu Wang (ziyuwang1) said on 2022-02-25:

Hi Luc,
I have read the paper[1].I understand most of them, but I don't know how to calculate the coordination number N.

As mentioned in the paper, the coordination number N and γ Int related.For example,I set InsertionSortCollider([Bo1_Sphere_Aabb(aabbEnlargeFactor=1.15) to increase this value,so how to calculate the N?

Thanks for help!

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