the stability of natural slope,cut slope and fill slope 1

[ananan88]

Dear friends:
I want to know if there are some differences among the stability of a natural slope,a cut slope and a fill slope whose size and soil parameters are all same.
If i analyse their stability without thinking of the consolidation of the soils, are their stability same?Or,I want to know if i must think of the consolidation of cut slope and fill slope.
Can i do the stability analysis by using the strength reduction method(SRM)?When the gravity of the slope is adding for the fill slope and reducing for the cut slope,how can i reduce the strength parameters of these slopein SRM?

 

[GeoPaveTraffic]

While there are often/usually differences between natural slopes, cut slopes, and fill slopes they can all be modeled the same way with slope stability programs. The differences are generally in strengths and piezometeric levels. I have never considered consolidation as part of a stability analysis. However, it is a good idea to look at it for large fill slopes.

As for SRM, I'm not familure with, by that name at least. Could you provide some additional information on the method?

 

[ananan88]

You can see my post:"Geotechnical Engineers Area - Slope stability engineering Forum wenandsky88 (Civil/Environme)18 replies9/7/04 (posted 7/7) how to get factor of safety of slope based on finite element analysis".There are some discusstion about SRM.

As to cut slopes and fill slopes,is there some difference whether I consider the whole construction process or not?I think the factors of safety are different considering the consolidation of the soils.How about not considering the consolidation of the soils?

 

[GeoPaveTraffic]

Thanks for the info on SRM, I thought it might be a finite element method for slope stability.

As for the cut/fill question. If you are using a finite element method, then there will be differences between a slope formed by cutting and one formed by filling. Note that these differences extend to natural slopes, i.e. a natural slope formed by cutting will behave diffently than one formed by filling. That of course is the theoretical answer. From a pratical stand point unless the slope is quite tall, I would say 75 feet or more, it is unlikely that the difference will be significant.

Also, you would have to have a lot of information about how the cut/fill was done; how long it took, piezo level changes, etc. to model the differences.

If you are using a standard limit equilbrium analysis there will be no meaningfull difference between natural, cut, and fill slopes.

 

[dirtsqueezer]

I'm not sure about SRM either. I have just a little plug for natural slopes, and some comments.

All things being equal, I think your natural slope will provide the most information regarding stability. The undisturbed slope will have undergone the test of time that will reveal tendancies of slumping, cracking, or in better cases holding a steep slope, and will also have vegetation to speak for stability or lack thereof. A cut slope may expose soils that respond poorly to weathering elements. Your fill slope will of course be more susceptible to weathering given the same soil type, given it's had less time to consolidate than either the natural or cut slope. I've done most of my work in Washinton State.

I would say you're dealing with two different questions, though if you were to ask about just the cut/fill, I think your stability may have more to do with soil type than anything. For example, a sandy gravel will experience much less consolidation for a cut/fill than, of course, a sandy clay.

Hope that helps! Happy digging.