Load carrying capacity of foundations

This paper addresses developments over the last 50 years, since Skempton's early contributions on the bearing capacity of shallow and embedded foundations, and focuses in particular on the gradual replacement of semi-empirical design approaches by more rigorous analytical or numerical solutions. Bearing capacity factors for shallow foundations on clay and sand are summarised from recent publications, taking account of foundation geometry and embedment, and variation of strength with depth. The effects on bearing capacity of other aspects of soil response are discussed, including strength anisotropy, consolidation under preload and compressibility. Traditional ways of evaluating foundation capacity under inclined or eccentric loading are being replaced by the use of interaction diagrams in vertical, moment and horizontal loading space; examples of these are presented. While the capacity of pile foundations is outside the scope of the paper, the trend towards the use of a small number of ‘settlement reducing’ piles beneath a raft foundation is discussed.