Effect of footing—soil interface friction on bearing capacity factor Nγ

Abstract

INTRODUCTION It is known that the magnitudes of the bearing capacity factors Nc and Nq remain almost independent with respect to changes in the roughness of the footing–soil interface (Meyerhof, 1957, 1963; Griffiths, 1982; Bolton & Lau, 1993). However, a considerable difference does exist between the magnitudes of Na for perfectly smooth and perfectly rough foundations (Meyerhof, 1957, 1963; Bolton & Lau, 1993; Michalowski, 1997). A footing–soil interface is considered perfectly smooth if a free relative movement can take place between the footing and underlying soil mass without the development of any interface shear stress. By contrast, the perfectly rough interface does not allow any relative movement along the footing–soil interface. Based on the theory of plasticity, the bearing capacity factor Na is often determined with the help of three different failure mechanisms: