Discussion of 'Correlations for Fully Softened Shear Strength Parameters' by B. A. Castellanos, T. L. Brandon, and D. R. VandenBerge, This Article Was Published in Geotechnical Testing Journal, Vol. 39, No. 4, 2016. [DOI: 10.1520/GTJ20150184]

摘要

In this paper, the authors criticize the use of a torsional ring shear device for measuring the fully softened strength (FSS) of fine-grained soils based on problematic ring shear data from Castellanos (2014). This is unfortunate and necessitated taking important time and energy to write this discussion. I have over 26 years of commercial soil testing experience while managing the Woodward-Clyde Consultants and AECOM Technical Services Laboratory in Santa Ana, California. I started performing Bromhead torsional ring shear tests to measure the residual strength (RS) of shear surfaces for landslides in 1991. As Professor Stark expanded his shear strength correlations and the geotechnical engineering practice embraced the use of FSS in stability analyses, I started using the Bromhead torsional ring shear device for FSS testing in 2009. The RS and FSS tests are performed in accordance with ASTM D6467, Standard Test Method for Torsional Ring Shear Test to Determine Drained Residual Shear Strength of Cohesive Soils, and ASTM D7608, Standard Test Method for Torsional Ring Shear Test to Determine Drained Fully Softened Shear Strength and Nonlinear Strength Envelope of Cohesive Soils (Using Normally Consolidated Specimen) for Slopes with No Preexisting Shear Surfaces, test methods, respectively.