The Application of Residual Shear Strength to the Design of Cuttings in Overconsolidated Fissured Clays

摘要

The report considers the factors which govern the long-term stability of the slopes of road cuttings in overconsolidated fissured clays and indicates the main topics on which further research effort is required. The concept of progressive reduction in strength from the peak to the residual condition in these soils is considered together with possible failure mechanisms. The extent of the main overconsolidated fissured clay formations is indicated and a regional-geological classification, based on the variation in the residual strength, is suggested. A more rational approach to the design of road cuttings and earth-retaining structures is suggested if the rate of reduction in shear strength for the main overconsolidated fissured clay formations can first be determined. A comparison is made of the slopes resulting from conventional designs based on the peak shear strengths with those based on lower intermediate values between the peak and the residual shear strengths. Finally this Report considers the situations in which the residual shear strength should be used at the present time. (Author)