CEEN 341 - Lecture 22 - PQ Diagrams, Sensitive Clays, and Thixotropy

This lesson combines a few unrelated (but important!) topics from geotechnical engineering. First, the basic concept of PQ diagrams (or stress paths) are introduced. You are shown how to compute Mohr-Coulomb strength parameters (i.e., c and phi) from a PQ diagram. Second, the topic of sensitivity in shear strength is introduced. Quick clays are discussed and their formation is summarized. Finally, the topic of thixotropy is briefly summarized.
Here is the link to the Rissa Landslide video (...an old video produced by the Norwegian Geotechnical Institute): • The Quick Clay Landsli...
Learning Objectives:
1) Transform a series of Mohr-circles to PQ space and calculate modified strength parameters;
2) Use the modified strength parameters to compute Mohr-Coulomb shear strength parameters c and phi;
3) Compute the sensitivity of a soil;
4) Describe what a quick clay is and how it is formed; and
5) Explain what thixotropy is

[@kururukaka]

As a fresh Junior Geotechnical Engineer, this lecture was a good recall. I used to learn this in year-2 at University, and haven't been covered for 4-5 years afterwards. Very informative and amazing lecture. Thanks for posing the well quality videos. I've watched all 22 lectures.

[@user-kb6xf6yc5e]

Dear sir, I'd like to express my gratitude for all of these valuable and neat lectures. They are very illustrative, comprehensive and smooth.

[@vercingetorix9005]

Oh dear Christ, you sir are an absolute live-saver. I can't thank you enough.

[@manuelpasmor17]

I love you so much, professor 😄 a big hug from the other side of the continent.

[@officehours4028]

Thanks! 😃

[@francescoa.francoalva7755]

Excelentísima clase. Muchísimas gracias por mi parte y mis compañeros de la facultad que adoramos tus videos.

[@officehours4028]

De nada!!

[@nabeelabdoola1057]

Writing from South Africa. Thank you so much for these videos. Could you please do a lecture on slope stability ?
I enjoy your explanations and the additional practical examples that you give as you speak.

[@dutoitfj]

Hi Nabeel, do you still have questions about slope stability?

[@CamiloPrada24]

Very interesting topics, great lecture. With the help of God we will continue to fight against COVID. Can a retrogressive failure mechanism of the magnitude of the Rissa landslide occur in other types of soils?

[@officehours4028]

Yes, it can occur in any type of soil that is very sensitive or quick. The magnitude of its occurrence at Rissa was intensified because of the local topography and population.