Reflections on C. H. Gregory' s New Cross landslide of 1841

摘要

The paper by C. H. Gregory in the Proceedings of the ICE for 1844, which describes the failures of a cut slope at New Cross some 3 years earlier, is a classic. It is included in full in "A Century of Soil Mechanics", and is referred to by Skempton (1979) in "Landmarks in Early Soil Mechanics". Gregory provides us with a detailed cross section of one of the slides, showing the position of the slip surface, which follows a particular horizon in the lowermost beds of the London Clay along part of its length. The cross section also indicates that the slide developed with a graben, and that the slide mass was full of internal shears. This paper starts with a critical review of Gregory's paper, and presents a series of back-analyses of the slide using both limit-equilibrium and continuum methods of analysis, and the results of these analyses are placed in the context of theories of delayed failures of cut slopes developed by Skempton and others. Particular attention is given to the equilibration of undrained pore suctions in the slope adjacent to the base of the London Clay.