Estimation of bearing capacity of circular footings on sands based on cone penetration test

In the present paper, the estimation of limit unit bearing capacity q(bL) of axially loaded circular footings on sands based on cone penetration test cone resistance q(c) is examined. There are significant uncertainties in the calculation of bearing capacity using the bearing capacity equation. The selection of the value of the soil friction angle phi and of the equation for N gamma accounts for much of the overall uncertainty. The approach proposed in this study can reduce the uncertainties associated with the bearing capacity equation, as no estimation of phi or selection of an equation for N gamma is necessary. Instead, normalized limit unit bearing capacities q(bL)/q(c) are calculated from non-linear finite element and cone penetration resistance analyses for various soil and footing conditions. Effects of the relative density D-R, the lateral earth pressure ratio K-0. and the footing size are also addressed. It is observed that the normalized limit unit bearing capacity q(bL)/q(c) decreases as D-R increases and that this rate of decrease of q(bL)/q(c) varies with K-0. Values of q(bL)/q(c) are presented both in equation form and in charts. The values of normalized allowable unit load q(b.all)/q(c) at a settlement of 25 mm for various soil and stress states are also provided.