INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!

*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.

Jobs

Difference Between Simplied Janbu and Bishop Slope Stability Methods

Difference Between Simplied Janbu and Bishop Slope Stability Methods

(OP)
I understand that in Bishop Slope Stability Analysis we are determining a FS based on moment equilibrium. In the Janbu Method we are determining based on force equilibrium. What I am having trouble determining is the merits of each and when one method would prove more applicable than the other.

RE: Difference Between Simplied Janbu and Bishop Slope Stability Methods

With moderen slope stability software neither method is generally recommended or used. Although Bishop's method is occationally used. These older methods were used when calculations were done by hand.

Either Spencer's procedure or the Morgenstern-Price method is most commonly used since both these methods satisfy both force and moment equilibrium.

Mike Lambert

RE: Difference Between Simplied Janbu and Bishop Slope Stability Methods

(OP)
I find that very interesting. In this region of the country (mid-atlantic) I have only ever seen Bishop method via GStable being utilized. Are there any references to specific jurisdictions, DOTs, or other organizations requiring Spencer's procedure or the Morgenstern-Price method in lieu of Bishop or Janbu?

RE: Difference Between Simplied Janbu and Bishop Slope Stability Methods

Most U.S. Army Corps of Engineer (USACE) Districts require Spenser's method. Spenser's is also recommended by the USACE Engineering Manual. California Department of Natural Resources requires either Spencer's or M-P, don't remember which off the top of my head.

If you are using a moderen slope stability program, I'm not familiar with GStable, there is no reason not to use a moderen analysis method. The only time I conider using Bishop's method is when I have a small slope with high undrained shear strength that is stable by inspection, but I have to determine and report a factor of safety (usually in the 4 to 10 range). Bishop's method will happly report a FS when more exact methods will indicate a tension crack is required that is deeper than the slope is high.

Mike Lambert

RE: Difference Between Simplied Janbu and Bishop Slope Stability Methods

(OP)
I was looking at some examples in Virginia. VDOT calls out the use of Modified Bishop, simplified Janbu, or Spencer Methods. I can say that in my 8 years in the industry I don't think I've seen a Spencer Method analysis in a report.

Can anyone recommend any good specific literature or references for global stability analyses? I have a good number of geotechnical references, but they are all kind of lacking in regard to global stability.

RE: Difference Between Simplied Janbu and Bishop Slope Stability Methods

I'm not sure what you are looking for. If you are looking for a reference that says use method A for situation X and method B for situation Y; then I think you are out of luck.

There is a lengthly discussion of different analysis methods in Appendix C of EM 1110-2-1902 which is the USACE slope stabiltity design manual. Page C-39 has a summary of several different methods. A copy of the manual can be downloaded here: http://www.publications.usace.army.mil/USACEPublic...

Other than the USACE manuals, I do not have a good reference for slope stability analysis. I will say that it takes a lot of experience to be good at it and that experience only comes from performing many hundreds of anlayses.

Let me know if you are looking form more specifics after you look at the EM and I'll try and help out.

mike

Mike Lambert

RE: Difference Between Simplied Janbu and Bishop Slope Stability Methods

(OP)
moe333, thank you for that video. It was fantastic and offered some great insights.

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!


Resources


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