Discussion of “Drained Residual Strength of Cohesive Soils” by Timothy D. Stark and Hisham T. Eid

Abstract

The authors have prepared an important paper on the drained residual shear strength of cohesive soil. The authors have developed a chart (Fig. 4) that can be used to determine the drained residual friction angle for different values ofliquid limit, clay fraction, and effective normal stress. Skempton (1964) stated that the residual friction angle is independent of the original shear strength, water content, and liquidity index, and depends only on the size, shape, and mineralogical composition of the constituent particles. The authors' correlation (Fig. 4) attempts to account for the size, shape, and mineralogical composition of the constituent particles through the use of the liquid limit and clay content. The authors present two case histories, the Gardiner Dam and the Portuguese Bend Landslide, where the back-calculated residual friction angles from stability analyses were almost identical to the values from the authors' correlation (Fig. 4). Three additional case histories are as follows. Slide at River Beas Valley