Minimum factor of safety

BC93 · Mar 16, 2011

Hello,

According to Geoslope manual (I guess you would find the same explaination in other manuals or books) "the contours indicate
that the minimum safety factor has been found."
I don't really understand - geometrically or physically - why having a FoS contoured implies that the minumum has been found.

Could it be that, as you go away from this FoS, the radius increases, most likely the length of the slip surface too, and in turn the shear resistance?
Thanks!

Ben

SixDegrees · Mar 16, 2011

I agree with you that the contours should not indicate a minimum factor of safety has been found.

For a simple slope, with constant radius surfaces the statement may make sense. But how do you plot contours for differing radius from the same center, or for that matter contours for block surfaces (which are more often that not give lower factors of safety).

The contours are a nice way of plotting the results,and show that you looked at a lot of surfaces. You still have to use your judgment to convince yourself you have found the minimum.

AussieGeoEng · Mar 16, 2011

I usually alway do a check with entry and exit or auto locate functions in slope/w. The key to using entry and exit is make sure you have defined enough entry and exit points, and enough radiuses.

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Minimum factor of safety

BC93

Geotechnical

SixDegrees

Geotechnical

AussieGeoEng

Geotechnical

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