Residual shear strength with special reference to rate effects

This thesis sets out to investigate and resolve a number of technical issues relating to the residual shear strength of clay soils. For this research the principal objectives concerned strain rate effects using the Bromhead Ring Shear and associated other factors their effects on residual shear strength, replication of the stress path and the homogeneity of clay. The principal areas of investigation are concerned with effects of varying rates of strain on residual shear strength, influence of "stress path" in determining residual shear strength and innate variability of residual strength in natural strata. Finally the principal conclusions were that the Ring Shear was excellent for British Landslides but at high strain rates there were problems with pore water movement and extrusion which are artefacts of the design. Stepless application of normal stress reduces these effects as it removes extreme stress changes. Clay strata are non homogeneous hence the requirement for continuous characterization tests.