Estimation of Bearing Capacity of Circular Footings on Sands Based on Cone Penetration Test

Abstract

In the present paper, the estimation of limit unit bearing capacity qbL of axially loaded circular footings on sands based on cone penetration test cone resistance qc 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 ϕ and of the equation for Nγ 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 ϕ or selection of an equation for Nγ is necessary. Instead, normalized limit unit bearing capacities qbL∕qc are calculated from non-linear finite element and cone penetration resistance analyses for various soil and footing conditions. Effects of the relative density DR, the lateral earth pressure ratio K0, and the footing size are also addressed. It is observed that the normalized limit unit bearing capacity qbL∕qc decreases as DR increases and that this rate of decrease of qbL∕qc varies with K0. Values of qbL∕qc are presented both in equation form and in charts. The values of normalized allowable unit load qb,all∕qc at a settlement of 25mm for various soil and stress states are also provided.