Slope Stability Soil Parameters?
Slope Stability Soil Parameters?
(OP)
I am required to do a slope stability in Illinois on a surface that is currently filled with construction debris. i.e. crushed concrete, brick, soil, etc. I am going to perform the slope stability using the wedge method, however, I was wondering if anybody had any input on some conservative values for the soil parameters and properties that I could input into the program. Also, if you have any idea of material that I could reference as to why I used the values I did. Any help would be greatly appreciated.





RE: Slope Stability Soil Parameters?
RE: Slope Stability Soil Parameters?
RE: Slope Stability Soil Parameters?
RE: Slope Stability Soil Parameters?
This is one of those problems I try to avoid...
GeoPaveTraffic and PEinc have given good advice. From a design standpoint, I'd use very low stength parameters (c=0, φ≤13° or so) and a "high" unit weight. Even if the lab work indicated the soils were significantly stronger.
And I'd use a higher factor of safety in an effort to reduce the apparent risk -
Of course, a better way to approach this might be to use Mike Duncan's reliability approach...
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See FAQ158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"
RE: Slope Stability Soil Parameters?
RE: Slope Stability Soil Parameters?
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See FAQ158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"
RE: Slope Stability Soil Parameters?
1. What does the physical cross section look like? I don't know if you are making a cut into the material for say, an open excavation, or you have a current embankment situation and wish to confirm the factor of safety that you have in place presently - perhaps for code upgrades for seismic, etc.
2. Part and parcel of 1., then, is how high is the slope and at what angles do you have/or will cut to.
3. Where is the groundwater level? Is there a perched level in the slope?
4. Assuming you have an existing slope, what is the chance of flooding (if any) for short or medium term against the slope face. Construction debris is likely so permeable that any flood water may almost immediately saturate your embankment. Do you have a condition where flooding might occur increasing the water level in the embankment and then get quick drawdown of the flood-levels so that you still have "water" in the embankment.
5. Is this a 2-D (plane) problem or is there any 3-D effects that might come into play.
6. If you have a "dry" embankment sitting at a certain "angle", this might give you an idea of minimum "angle of repose" - hence, to a start, possible overall strength values.
You see, doing a stability analysis is more than just applying a set of strength parameters and running an infinite slope analysis or using the computer to generate a critical surface. There are many other factors that you must understand before you can make a judgment on the stability of the slope - and one of them, in the case of infinite-type slope assessments, is the "critical mass" of which you would be concerned - clearly you wouldn't be concerned about 500mm sheet-type failure (unless there is a reason for progressive ones).
RE: Slope Stability Soil Parameters?