Second-moment characterization of undrained shear strengths from different test procedures

Abstract

The undrained shear strength (su) of a clay is not a constant. In particular, su of a clay evaluated by different test procedures are different because these tests may have different stress states, stress histories, degrees of sampling disturbance, and strain rates. This study summarizes the mean value and variability of the normalized undrained shear strength (su/σ'v) from various test procedures based on a large clay database. These second-moment statistics can be seen as a probabilistic extension of Eq-4.55 developed in Kulhawy & Mayne (1990), which provides an estimation of the normalized undrained shear strength based on three factors accounting for test mode, overconsolidation ratio, and strain rate. The second-moment statistics are essential for reliability analysis and reliability-based design. © 2013 American Society of Civil Engineers.