L30 Mohr-Coulomb, Dracker-Prager, and Modified Lade yield criteria

Lecture 30 of PGE 383 (Fall 2020) Advanced Geomechanics at The University of Texas at Austin delivered on 2020/10/28 by DN Espinoza ( / dnegeomechanics .
Topics: stress-sensitive yield criteria, frictional strength, Mohr-Coulomb failure criterion, extension to Drucker-Prager and modified Tresca, axisymmetric triaxial tests, modified Lade criterion.
More about the triaxial tests: Section 4.3.4 in dnicolasespino...

[@jhonathanhenaoossa2828]

Clear lecture professor Espinoza.... useful for my class on mechanical behavior!

[@loknathdas3111]

Best lecture on youtube. so much clarity in the explanation, thank you vary much

[@clem5474]

Master class.. 👏👏

[@JosueA_455]

Context - Minute 15.20. How would you explain that from s1 in the M-C plot the characteristic angle can be found in the counterclockwise direction whereas it is clockwise in the 2D representation?

[@dnicolasespinoza5258]

I don't think it in terms of clockwise or counterclockwise, I think it always as going from the point/plane of sigma_1 to point/plane of sigma_3 (or any other principal stresses). It never fails.

[@suryaprasanthmuddana7038]

sir one doubt...how can we draw simply a circle on hydrostatic axis in drucker prager ? you said it should be symmetric with hydrostatic axis then why only circle ? please clarify sir.

[@dnicolasespinoza5258]

It is not a single circle, it is a conical surface in the principal-stress-space where the cone axis coincides with the hydrostatic axis. The circle is just a cross-section of the cone with a plane perpendicular to the hydrostatic axis. I hope this helps.

[@MacCionnaith]

Thank you so much!

[@karlmartinsmusic]

Good morning, professor. Your lectures are amazing. Do your lectures follow any book? Could you recommend one? Best regards.

[@dnicolasespinoza5258]

Hi, I have a video describing the main books I follow: kzbin.info/www/bejne/qZbZpn6epJWErbM . There are some advanced topics that have been covered in very recent papers. Click "SHOW MORE" in the corresponding video and you will find the citations for the papers I refer to in that lecture, if any. Thanks for watching!

[@loknathdas3111]

sir, can you please, upload videos comparing mohr coulomb and Cam Clay model

[@kouroshgashtil2989]

Thanks for the video , Do you have any video about lode angle and STRESS Triaxiality on your channel? If not , Would you please do me a favor and explain a bit about them? thank you.

[@dnicolasespinoza5258]

Hi, I talk about stress invariants here: kzbin.info/www/bejne/gHazeJ9ol9WEo7s . I don't mention the Lode angle but have added it to my list of future videos. Thanks for the suggestion!

[@0713059059]

Hi Professor. How the behaviour of rock vary from the behaviour of soils? Are there any differences using these constitutive models for soil?

[@dnicolasespinoza5258]

The main difference is cementation which provides rock with cohesive strength. In general, all materials have a tension limit, compression yield cap, and some frictional strength. Tresca and von Mises (for metals), are a particular case of Drucker-Prager/Lade (rocks), which in turn are a particular case of more advanced models like Cam-Clay or Kayenta (for soil and rock/soil at high stresses). Which model you choose depends on the range of your stresses and what kind of inelasticity you want to capture.

[@0713059059]

@@dnicolasespinoza5258 Your explanation makes sense. Love your channel. Keep posting!

[@NavyaRana-h7c]

🎉

[@marembomicheal176]

Hello prof. Thank you so much for the educative series. Is there a way I can implement this failure criteria in comsol or any geomechanics of a rock. Any link guiding me on how to implement in comsol would be helpful. Thank you

[@dnicolasespinoza5258]

Yes, you can: www.comsol.com/blogs/how-to-implement-elastoplasticity-in-a-model-using-external-materials/ . However, this might an "additional" package the requires a license upgrade.