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Alec Westley Skempton 1914-2001

sdfhtProfessor Sir Alec Westley Skempton FREng FRS, one of the founding fathers of the discipline of soil mechanics, died on 9th August 2001. Known to all as “Skem”, he came to prominence in the 1940s as a result of the work of the Soil Mechanics Group at the (then) Building Research Station. In 1947 he moved to Imperial College, becoming Professor of Soil Mechanics in 1955 and Professor and Head of Department of Civil Engineering in1957, posts he retained until his retirement in 1981. Thereafter he had a room at Imperial, where he attended almost daily until a month or so before his death. From the late 1930s to the mid 1990s he published a succession of benchmark papers on a wide range of geotechnical subjects. In the last few years he was as active as ever, though his interests were concentrated on the history of civil engineering.

Skempton was born on 4th June 1914, in Northampton, the only child of Alec and Beatrice Skempton. He attended Northampton Grammar School, and became an undergraduate in the Department of Civil Engineering at Imperial College in 1932. He graduated with First Class honours in 1935.

Though as an undergraduate he particularly enjoyed geology, he remained at Imperial to carry out research on reinforced concrete. In 1936 he moved to the Building Research Station (BRS) to continue research on concrete. At BRS a soil physics section had been formed 1933, which soon became the soil mechanics section. This Skempton joined within months of his arrival at BRS, working there for the next ten years.

Geotechnical Contributions

Skempton’s style of research was to address individual case studies, carrying out the appropriate investigation, and then write up the results. The more fundamental aspects of these case studies regularly evolved into seminal papers. His early work involved the classification of, and inter-relationships between soil properties. Ir was he who recognised that geologically normally consolidated clays exhibit an increasing strength with depth, and that undrained strength would normalise with vertical stress, so that the ratio c/p (Skempton’s terminology) was constant with depth, and could also be correlated with plasticity index.

This interest in the in-situ behaviour of natural clays led to two papers delivered at the Geological Society (1944 and 1970), on the geological compaction of natural clays, the latter of which was undoubtedly one of his major contributions. From about 1953 he began to concentrate on the subject of slope stability. The residual strength of clays is the topic with which Skempton will always be associated, and the subject of his Rankine Lecture (1964). In this he demonstrated that residual strength was a fundamental property, dependant, inter alia, on the mineralogy of the soil. This lecture was undoubtedly Skempton’s most important single contribution to soil mechanics. He later revealed the history behind the development of these ideas in a paper in the Quarterly Journal of Engineering Geology.

His most productive period, at least for his work in geotechnics, was during the late 1950’s and 1960’s. Consulting work resulted in a paper on the allowable settlements of buildings (1956), which is still widely used, as is the pragmatic “α-method” (1959) for the design of bored piles in London Clay. He wrote an influential assessment of horizontal stresses in the London Clay (1961), and published an analysis of effective stresses in soils and rocks (1960). His concept of A and B pore pressure coefficients (1954) is still widely used. He was one of the first to examine the effects of stress relief on the stress-strain-strength behaviour of clays (1963). This series of papers is perhaps the most influential ever published in the subject of soil mechanics by an individual.

Consulting work

Skempton’s advice as consultant was widely sought. He was involved with a number of embankment dam schemes, including Chew Stoke, for which he assisted in the design of sand-drains to accelerate consolidation of the weak alluvial foundations, the first such in the UK. For many years he worked with Binnie and Partners (now Binnie Black & Veatch), his first commission being Usk Dam (1951), though the most important was Mangla dam in Pakistan (1958-67), where his recognition of tectonically sheared zones in the dam foundations was crucial.

In 1984 he reviewed the failure of Carsington Dam, Derbyshire, his studies of which were published in 1985 and 1991. He advised on the foundation performance of Waterloo Bridge, London, the Tower of Pisa, Italy, and both St Paul’s Cathedral, London and Salisbury Cathedral. Large landslides on which he advised included Sevenoaks, published in the proceedings of a Royal Society Discussion Meeting on valley slopes, which he organised. This paper is of particular interest as it demonstrates his considerable understanding of Quaternary geology.

History of Civil Engineering

Skempton’s civil engineering history studies almost single-handedly transformed the subject a rigorous academic discipline. His approach is typified by his first historical paper (1946), to the Newcomen Society, reviewing the work of Alexander Collin, who in the 1830’s carried out systematic investigations of clay slips.

When he retired, Skempton had begun to work on a history of soil mechanics. As a project this was soon shelved, but he became chairman of the editorial panel for a “Biographical Dictionary of Civil Engineers in Great Britain and Ireland during 1500-1830”. The writing and editing of this occupied him for much of the last five years of his life. Though he did not live to see its final publication, he was correcting the proofs a few days before he died, and had the satisfaction of knowing that this major work was all but complete.


Honours were many, including Fellowship of the Royal Society, and Founder Fellowship of the Royal Academy of Engineering. He was the second President of the International Society of Soil Mechanics and Foundation Engineering (1957-61), in succession to Karl Terzaghi. His wide range of interests was reflected in his medals and awards: the Ewing Gold Medal (Institution of Civil Engineers), the Lyell Medal of the Geological Society, the Dickinson Medal of the Newcomen Society, the Terzaghi Award of the American Society of Civil Engineers, and the Gold Medal of the Institution of Structural Engineers. Honorary Doctorates were awarded by the Universities of Durham, Aston and Chalmers University, Sweden. His ultimate accolade was the knighthood he received in the Millennium Honours List in January 2000.

In 1940 he married Mary (Nancy) Wood, a graduate of the Royal College of Arts, who pre-deceased him. He leaves two daughters, Judith and Katherine, five grandchildren and his partner Beverley Beattie. An extended obituary and complete bibliography appear in Géotechnique (volume 51, pages 829-834).