Cut slopes & Fill slopes stability 2

[PujanG]

I'm new to this field & was wondering about the stability of cut & fill slopes. how much should be the slope to be stable? gentle is stable but steeper is economic.
without any experience of similar kind, I can only rely on literature; which suggests that i should perform slope stability analysis( friction circle method). But this would require me to obtain soil parameters like c, phi; which we can't afford due to economic reasons.
so what is in practice? how can i determine a stable economic fill /cut slopes based on visual inspection of soil? Are there any software or code for this purpose?

Thank you!

 

[Ron]

PujanG....step back a bit and think about what you are asking. Slope stability depends on the soil conditions. You cannot determine its stability without knowing something about the soil characteristics. You can determine this through a geotechnical investigation, visual assessment in the field and historical information for the area. Your risk goes up with each of these variations with the lower risk being the use of site-specific geotechnical investigation information. If you were experienced at field characterization of soil characteristics, you could do some limited field investigation on your own and determine enough to do a stability analysis; however, it does not seem that you have such experience as that appears to be your motivation for the query here.

Sometimes there are no reasonable shortcuts. With each shortcut you take, there is risk involved. The better your experience and judgment, the lower that risk becomes. In your case, it would be good for your experience to obtain the proper field information so that you could gain the experience in using such information for a proper analysis. Absent that, you are taking a risk, exposing your company to risk and exposing your client to risk. You might get lucky...but then again, you might not.

If you do not have a more senior engineer with whom you can consult and receive mentorship in this issue, I would suggest that you not attempt a potentially risky design analysis. If you client will not pay for a proper investigation, then perhaps you don't need that client.

Good luck.