How do you calculate the soil bearing pressure?
The horizontal pressures on the backfill side will produce an overturning moment with respect to the base of the footing. This overturning moment must be resisted by an opposite resisting moment produced by the vertical forces, including the wall selfweight and the weight of the backfill over the heel.
When the eccentricity falls within the kern = L / 6, the entire footing is under compression and the bearing diagram is a trapeze, as shown in the example above. In this case the maximum bearing pressure is Rv / L + 6 * Rv * e / L2.
When the eccentricity falls outside the kern, the footing is under partial bearing and the diagram is a triangle. In this case the maximum bearing pressure is Rv / (0.75 * L – 1.5 * e).