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

다국어 초록 (Multilingual Abstract)

<P><B>ABSTRACT</B></P> <P>The initial, linear elastic range of a soil stress-strain curve is often defined by the small-strain elastic modulus <I>E</I> <SUB>0</SUB> or shear modulus <I>G</I> <SUB>0</SUB>. 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 <I>q</I> <SUB>c</SUB>. 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 <I>G</I> <SUB>0</SUB>-<I>q</I> <SUB>c</SUB> correlations available in the literature were evaluated. For isotropic conditions, both correlations produced reasonably good estimates of <I>G</I> <SUB>0</SUB> for clean sands but overestimated it for silty sands. A <I>G</I> <SUB>0</SUB>-<I>q</I> <SUB>c</SUB> correlation which is proposed takes into account the effect of silt content of the sand and stress anisotropy.</P>