Estimation of the Small-Strain Stiffness of Clean and Silty Sands using Stress-Strain Curves and CPT Cone Resistance

Abstract

ABSTRACT The initial, linear elastic range of a soil stress-strain curve is often defined by the small-strain elastic modulus E0 or shear modulus G0. In the present study, simpler and effective methods are proposed for the estimation of the small-strain stiffness of clean and silty sands; these are based on triaxial compression test results and the CPT cone resistance qc. In the method based on stress-strain curves obtained from triaxial compression tests, an extrapolation technique is adopted within the small-strain range of a transformed stress-strain curve to obtain estimates of the small-strain elastic modulus. Calculated small-strain elastic modulus values were compared with the values measured using bender element tests performed on clean sands and sands containing nonplastic fines. The results showed that the method proposed produces satisfactory estimates of the small-strain elastic modulus for practical purposes. In the CPT-based method, two G0-qc correlations available in the literature were evaluated. For isotropic conditions, both correlations produced reasonably good estimates of G0 for clean sands but overestimated it for silty sands. A G0-qc correlation which is proposed takes into account the effect of silt content of the sand and stress anisotropy.