For cohesionless soil, the location of the groundwater table can affect the ultimate bearing capacity.
As mentioned in Sec. 3.4, the saturation of sand usually does not have much effect on the friction
angle (i.e., f′ ≅ f). But a groundwater table creates a buoyant condition in the soil which results
in less resistance of the soil and hence a lower ultimate bearing capacity. The depth of the bearing
capacity failure is rather shallow (Fig. 6.1 to 6.3) and it is often assumed that the soil involved in the
bearing capacity failure extends to a depth equal to B (footing width) below the bottom of the footing.
Thus for a groundwater table located in this zone, an adjustment to the ultimate bearing capacity
is performed by adjusting the unit weight of the second term of Eqs. 6.1 and 6.5 by using the
following equation (Myslivec and Kysela, 1978):