rankine failure plane ? start where stem meets footing or bottom corner of footing?

[meaty_matt P.E.]

Ncees geotec problem 510 shows the failure plane originating at the "overturning point" at the bottom corner of the footing.

Ncees geotec problem 528 shows the failure plane originating where the stem meets the footing.

Which is right and why?

Thanks

 

[meaty_matt P.E.]

Correctionrob 528 shows origination at the corner opposite overturning point

510 shows origination at rotation point for bearing capacity failure

 

[ketanco]

because in 510 it says "no additional lateral pressure may be applied to ANY part of the retaining wall"

if you draw the active wedge as in 528, then you are subjecting your walls heel (vertical face of heel plus the horizontal face of heel to the horizontal component of the force from embankment) to the force that is dissipated to the ground by embankment.

i had the same mistake on this question #510, because i took the active wedge as in 528....

and now I looked at this again based on your questioin and this is my understanding.

this should be the reason in my opinion.... do I make sense?