Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Use of saturated Mohr-Coulomb failure criterion and a water table

Use of saturated Mohr-Coulomb failure criterion and a water table

Use of saturated Mohr-Coulomb failure criterion and a water table

Hello all.

I have recently read a report where someone has conducted a slope stability assessment using the rocscience SLIDE software. For this analysis, they defined the material using mohr-coulomb c=40kPa, phi = 25deg which was derived from CU triaxial tests. This test type represents a saturated soil. Therefore, I was surprised to see that they also included a water table.

Now, I am not sure if I am getting confused here, but isn't this double accounting the groundwater within the soil? And if you have MC params from a CU triaxial, you already assume the soil is fully saturated and does not need a water table within the analysis?



RE: Use of saturated Mohr-Coulomb failure criterion and a water table

If you are running an effective stress slope stability analysis, then the water table needs to be included in the analysis because it influences the effective stresses, and thus the shear strength.

Shear strength = c’ + sigma’(tan(phi’))

If you were running a total stress analysis, the water table should not make a difference (a difference in the shear strength) because you are using total stresses.

RE: Use of saturated Mohr-Coulomb failure criterion and a water table

Based on the parameters provided to me this indicates a low plastic clay. Selecting the CU test is an indication of the long term steady state.

As an old engineer told me if you build a dam on soft clay you only need to be concerned for the first two years after construction. If it doesn't fail in the first two years the foundation Clay's have consolidated and gained strength.

The critical case is the end of construction case where all the pore pressure has not dissipated and how that is analyzed. In slope/w I have seen a b-bar used to increase the pore pressure.

RE: Use of saturated Mohr-Coulomb failure criterion and a water table

Thank's all for your replies to my question.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper - PLM and ERP: Their Respective Roles in Modern Manufacturing
Leading manufacturers are aligning their people, processes, and tools from initial product ideation through to field service. They do so by providing access to product and enterprise data in the context of each person’s domain expertise. However, it can be complicated and costly to unite engineering with the factory and supply chain. Download Now
White Paper - Medical Device Design Control
Medical device product development is a highly integrated and regulated process. Implementation of a requirements tracking solution requires attention to a variety of nuanced topics. When presented with the task of tracking the many concept relationships in a project of this type, the initial software solution of choice tends to be a two-dimensional text systems. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close