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 Φ and of the equation for N_γ 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 N_γ 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_O, 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_O. 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.