In this, EF failure surface is considered to be inclined at an angle of with the horizontal followed by FG which is logspiral curve and then the failure surface extends to the ground surface (GH).

EF is considered as a imaginary retaining wall face with failure surface as FGH. This problem is same as the retaining wall with the inclined backfill at an angle of α. For this case the passive earth pressure acting on the retaining wall is given by Caqnot and Kerisel (1856). Considering the equilibrium of the failure zone,


where,
is the load on the footing,
W is the weight of the active zone and,
is the vertical component of the passive pressure acting on walls JF and EF.
Then the ultimate bearing capacity is given as,

Where,
B is the width of the footing.
Comparing the above equation with,

We get ,
,