# Shear Strength Reduction vs Limit Equilibrium

**URL:** <https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105>\
**Category:** General\
**Created:** [September 21, 2021, 2:25pm UTC](https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105 "2021-09-21T14:25:03Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![jhazzard](https://avatars.discourse-cdn.com/v4/letter/j/4af34b/32.png) [@jhazzard](https://forum.itascainternational.com/u/jhazzard)\
**Post date:** [September 21, 2021, 2:25pm UTC](https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105/1 "2021-09-21T14:25:03Z")

</div>

Nice article on this from Rocscience [here](https://www.rocscience.com/about/news-events/open-secret-advantages-of-the-shear-strength-reduction-approach-in-slope-stability-analysis?utm_medium=email&utm_source=rocnews&utm_campaign=September2021).

---

<div class="post-metadata">

**Author:** ![stmicheljerome](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/stmicheljerome/32/127_2.png) [@stmicheljerome](https://forum.itascainternational.com/u/stmicheljerome)\
**Post date:** [March 3, 2022, 8:28pm UTC](https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105/2 "2022-03-03T20:28:16Z")

</div>

Hi everybody,

I’m new to this forum which prevents me from creating new topics. I figured out I could post my question regarding FLAC/SLOPE here.

The Itasca website states that FLAC/SLOPE can be used to run pseudostatic slope analysis, but I can’t find how. Since failure surface aren’t imposed to the model, I don’t understand how to apply an horizontal force that suppose to represent an earthquake.

Best regards,

Jerome

---

<div class="post-metadata">

**Author:** ![jwang](https://avatars.discourse-cdn.com/v4/letter/j/b782af/32.png) [@jwang](https://forum.itascainternational.com/u/jwang)\
**Post date:** [March 3, 2022, 10:15pm UTC](https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105/3 "2022-03-03T22:15:25Z")

</div>

Go to HELP-\>PDF manuals, open the FLAC/Slope Users’ Guide manual: Section:1.4.7 Pseudostatic Analysis.

---

<div class="post-metadata">

**Author:** ![stmicheljerome](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/stmicheljerome/32/127_2.png) [@stmicheljerome](https://forum.itascainternational.com/u/stmicheljerome)\
**Post date:** [March 4, 2022, 10:04pm UTC](https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105/4 "2022-03-04T22:04:11Z")

</div>

Thanks for your answer @jwang. I updated FLAC/SLOPE to the last version. I now have access this section 1.4.7 of the manual.

---

<div class="post-metadata">

**Author:** ![stmicheljerome](https://yyz1.discourse-cdn.com/flex031/user_avatar/forum.itascainternational.com/stmicheljerome/32/127_2.png) [@stmicheljerome](https://forum.itascainternational.com/u/stmicheljerome)\
**Post date:** [March 4, 2022, 10:09pm UTC](https://forum.itascainternational.com/t/shear-strength-reduction-vs-limit-equilibrium/105/5 "2022-03-04T22:09:56Z")

</div>

I ran a few analysis and I’m wondering if the given displacement associated with the FoS are realistic. I used FLAC instead of FLAC/SLOPE to run the analysis and corrected the default modulus given by FLAC/SLOPE with realistic values.

I read in the manual that the FoS is associated with a state of non-equilibrium which leads me to think that the displacement could be larger as the failure progresses…

Best regards,

Jerome