(ii) Non-Circular Failure Surface:

JANBU'S METHOD:

The difficulty in analysing a non-circular failure surface is that it is difficult to find a single point through which many of the force components act. So, the moment equilibrium method used for circular surfaces is no longer the most appropriate.

Janbu chose instead to use the force equilibrium method in the analysis which follows.

Following on further from Bishop's Method, we get:-