Analytical Model for the Ultimate Bearing Capacity of Foundations from Cone Resistance

Abstract

By application of Cone Penetration Test (CPT) data for shallow foundation (footing) design, the problems of providing representative undisturbed samples and, rather, varphi-N coefficient relations will be eliminated. An analytical model, based on a general shear failure mechanism of the logarithm spiral type, has been developed for calculating, directly, the bearing capacity of footings, q_ult from cone resistance, q_c. The transform of the failure mechanism from a shallow to a deep foundation and the scale effect have been considered in the proposed method. Six current CPT direct methods for determining the bearing capacity of footings have been investigated. The proposed method and others were compared to the measured capacity, ranging from 1.7 to 15 kg/cm^2, of 28 footings compiled in a database with a range of diameter from 0.3 to 3 m located in different soils. The graphical and cumulative probability approaches for the validation of the methods indicates optimistic results for the bearing capacity estimation of the proposed method, which is simple and routine.