Application of the Resistance Envelope Procedure to the Determination of Field Mobilised Shear Strength

Extensive case studies of existing stable slopes and a number of active landslides, most larger than a million cubic metres, are described. All slides are derived from the same parent material thus providing an appropriate basis for Casagrande's resistance envelope procedure to calculate field shear strengths. Subsurface investigations, piezometric monitoring, observation of displacements, and laboratory testing have enabled the successful application of resistance envelopes to the determination of reliable design parameters. This has provided a high level of confidence in the design of highway cut slopes, and in the predicted response of existing slides following submergence by reservoirs for hydro-electric development. The theory for application of resistance envelopes is developed further to allow determination of effective stress parameters applicable after saturation of partially saturated soils.