Charles Augustin de Coulomb, the artisan of modern geotechnical engineering

Abstract

The paper puts in perspective the influence of Charles-Augustin de Coulomb on the research and practice of modern geotechnical engineering. In his “Essai” (1773), Coulomb presented clear propositions on friction and cohesion on a sliding plane, giving birth to today’s soil mechanics. Coulomb’s theory started with the suggestion that the strength on a slip plane must involve a combination of friction and cohesion. Coulomb used calculus to obtain active earth pressure and show how friction and cohesion together affect lateral earth pressure. Coulomb was a gifted experimental scientist and wrote, when discussing friction, cohesion and interlocking that “only experiment can help us to decide the reality of the different causes” [for resistance]. With his fundamental equation [±t = c + µσ = c + tanϕ σ], Coulomb brought his theory to design. Design guidelines and standards are written in terms of cohesion and friction, and Coulomb’s fundamental slip plane model still dominates today’s soil mechanics. Coulomb’s insight led to further developments by Terzaghi, Hvorslev, Skempton, and the ensuing work at Imperial College and Cambridge University in the UK, at Harvard and at MIT (Lambe, Whitman, and Ladd) in the USA. Coulomb’s work, originally for masonry, has enabled the geotechnical profession to map soil behaviour, and continues to inspire new generations of researchers to look into improved and novel models and interpretations of the shear strength of soil and rock.