From Chingford to Carsington: impact of soil mechanics on dam construction, 1937-1987

Abstract

In 1937 the investigation of the failure during construction of Chingford No 2 embankment dam brought the concepts of modern soil mechanics to bear on the construction of British embankment dams. Effective stress theory highlighted the crucial significance of pore water pressure in understanding embankment stability and it became standard practice to monitor pore pressures during embankment construction using twin-tube hydraulic piezometers. By the 1980s embankment stability might have seemed assured, with embankment design utilising limit equilibrium stability analyses that incorporated strength parameters of fill and foundation materials determined by laboratory testing. However, in 1984 the upstream slope of Carsington dam suffered a major slip in the final stage of construction. Recently developed advanced finite element analyses were able to demonstrate that progressive failure was a major factor in the slope instability, but the failure was also a reminder of the continuing need for experience-based judgement in design.