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# slip circle

## slip circle

(OP)
hi.
Is anyone here have any idea how to find radius of slip circle without knowing all the parameter. I only have the information of the bank height which is 23.46m.
I am no specialist in geotech and I have difficulty to solve this. please help. Thank you

### RE: slip circle

your inquiry is very vague , provide more details with pictures or drawings

### RE: slip circle

If this is a serious project, and you have not done these types of stability studies before, this is best left to an experienced person. Lacking that you need a course in soil mechanics.

### RE: slip circle

A doctor can never diagnose a patient just by some text for ex . Geo technical engineer obeys the same rule

### RE: slip circle

Hi Saz, ican give the idea how to find radius of slip circle as follow:
firstly you have to hire a geotech engineer/technician to drill some holes to measure the strength of the soil.
secondly you have to measure the slope angle.
the last step you have to buy the geo-slope software to analyse the stability of your 23.46 bank height.
Finally you will find the critical slip circle.

### RE: slip circle

LOk - "you "have" to buy the geo-slope software?" Don't think so. People used to do these things by hand calc methods (probably way before your time - but go to Terzaghi and Peck (1967) to see tables on how to do it.).

The lad/lass has a bank height - well, true, that is one parameter. I would hope they know the angle of the slope. LOk is correct in that knowing the soil types and properties is necessary (to a degree which I will explain later). Also the stratigraphy.

First - is the slope of a cohesionless soil? (sand and gravel) - if so, there really isn't a "critical circle" involved as it is an infinite slope problem that will govern to provide the minimum factor of safety. Now if this is an embankment sitting on a soft or firm clay - then there would be a global stability problem - not just the slope itself.

If the soil is cohesive - many years ago, someone wrote a paper that would give you a near/close estimate as to the location of the critical slip surface "focal/centre point" - that point from which the critical radius. The paper I am thinking of was from the mid to late 60s - but Huang (1980) also provided a method - (Huang, Y.H. (1980), Stability charts for effective stress analysis of nonhomogeneous embankments, Transportation Research Record, 749, pp 72-74. you will find this explained in Fang's Foundation Engineering Handbook, 2nd Ed 1991.

So, in essence, there are ways (including many charts) that can be used to find the "critical" surface (or close) of relatively homogenous slopes. Of course, determining the factor of safety is dependent on knowing the properties; complex slopes/stratigrapies notwithstanding.

### RE: slip circle

Sazvon,
As BigH states, this analysis can be done using hand calcs and charts, although there is also relatively inexpensive software available these days also (SlopeW is not inexpensive). The software makes the analysis much quicker, but you should understand how the software works before using it, and you will need soil properties, stratigraphy, strength, groundwater conditions, and geometry for the charts or software.

A good, free manual for using chart solutions can be found here:

http://www.vulcanhammer.net/geotechnical/Duncan_19...

### RE: slip circle

Personally, I think that anyone doing computer slope analysis must be forced to do two or three different hand calcs - not to show how hard it was in the old days (and I sure did my share) but to get a feel for what is going on.

### RE: slip circle

You have to buy slope stability software if you want to make more than minimum wage to complete your study, lol!

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