Effective Stress Shear Strength Parameters From Piezocone

Effective stress shear strength parameters for cohesive soils are important parameters in geotechnical analysis and design. These parameters can be determined by carrying out consolidated undrained tests with porewater pressure measurements. Those parameters can be also determined based on interpretation of piezocone penetration tests. The current state of the art status had not reached to a level where reliable estimate of effective stress shear strength parameters can be made from the CPTU data. The aim of this paper is to provide additional data on both effective stress shear strength data measued from isotropically consolidated undrained triaxial tests and CPTU data for normally consolidated to slightly overconsolidated clay from the Nile delta deposits based on geotechnical investigations in nine major sites in Egypt. It is beleived that the addition of this data to the literature provides a better ground for improving the current state of the art of estimating effective stress shear strength parameters from the CPTU data. With such beleif, the data are used to evaluate and modify the available method(s). Such an exercise empirically contributed to judgment of angle of plastification and modification of bearing capacity factor, Nq, in the Senneset-Janbu method.