retaining structure and slope stability
retaining structure and slope stability
(OP)
Hello frs,
I have doubts regarding the design a retaining wall (say sheet pile)
Q1: Is slope stability analysis required even though there is a plan to provide retaining wall. If the earth is unstable, doesn't retaining wall provide stability for that earth. If the earth destabilizes and pushes the wall (H/200 ?),active pressure comes into the picture and by considering this pressure in the design we are stabilizing the soil. Am I wrong?
So do we still require slope stability analysis, please advice
Q2: If the earth behind the retaining structure is inclined and on top of the the inclined surface if there is a surcharge, meaning if there is an addition of heavy rock to create runoff channel, how is that weight considered. Can I consider that as a surcharge on the inclined fill and break them as vertical and horzz components and calculate the forces on the wall ?
I have doubts regarding the design a retaining wall (say sheet pile)
Q1: Is slope stability analysis required even though there is a plan to provide retaining wall. If the earth is unstable, doesn't retaining wall provide stability for that earth. If the earth destabilizes and pushes the wall (H/200 ?),active pressure comes into the picture and by considering this pressure in the design we are stabilizing the soil. Am I wrong?
So do we still require slope stability analysis, please advice
Q2: If the earth behind the retaining structure is inclined and on top of the the inclined surface if there is a surcharge, meaning if there is an addition of heavy rock to create runoff channel, how is that weight considered. Can I consider that as a surcharge on the inclined fill and break them as vertical and horzz components and calculate the forces on the wall ?






RE: retaining structure and slope stability
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: retaining structure and slope stability
Q2: Yes, with some limit as to height and distances. Check out a good Geotech text like Bowler or Days.
RE: retaining structure and slope stability
Q2: It depends on the degree of slope, length of slope, magnitude of surcharge, soil properties. Look at 'trial wedge' methods. They are simple and easy to put into spreadsheets for hand calcs. You can also get your answer from slope stability programs.
RE: retaining structure and slope stability
I am attaching a sketch of what I am dealing with
I was asked by client if they can avoid slope stability analysis performed on the slope. I want to say yes to fail conservative.
Adding to this, I was told the earth behind the sheet pile is Clay.
RE: retaining structure and slope stability
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: retaining structure and slope stability
Who would ultimately take responsibility for the final design of the retaining wall? I would not be comfortable with designing a retaining wall without considering local and global stability. The risk should be covered.
RE: retaining structure and slope stability
RE: retaining structure and slope stability
Q1: I believe the slope stability analysis is not as much for the completed structure, but for the structure during construction. If in the process of removing material you overcome the tensile strength of the local soil and incremental collapse (a slide) could result.
Q2: I handle sloping backfill by using Rankines equations, and any surcharge would act as you described (see 'Soil Mechanics & Foundations' Chapter 10 by Das for further clarification)
The report gave me more than the information I needed to go ahead and accept the job as well, it included most of the necessary geotec. information on the soils to do my local stability checks. A residence will be fairly close to my walls, so safety is my overall goal on this.
Contact your local authority and find out the requirements for slope stability analysis, in my jurisdiction if you don't include a slope stability and geotech report with every retaining wall you have to list good reasoning why. 'Because the client wanted to save a few bucks' probably wouldn't be accepted.
RE: retaining structure and slope stability
Most of the geotech books deal with cohesion less soils. Reading through some of the material, it became obvious that dealing with clay fill is not as simple as dealing with sand. There is a short term and long term pressure issues due to drained and un-drained conditions.
How did u guys deal with inclined clay fill
Signious
How did u deal as your case is similar to mine
RE: retaining structure and slope stability
Clay fill is outside of my area of expertise, so I am a little hesitant to give you solid advice on how to proceed. Perhaps a post or search in the 'Earth Retention Engineering' section could help.