Assessment of existing V_s-Lab correlations regarding Eastern Canadian clays

The small strain shear modulus, G_max, is an important parameter for characterizing the seismic response of deposits to dynamic loading. The parameter is related to shear wave velocity (G_max=ρV_s²) only via the soil density. Existing V_s correlations established in the laboratory were compiled in this paper and grouped into different general forms. Laboratory V_s measurements using the piezoelectric ring-actuator technique, P-RAT, incorporated in conventional oedometer cells, were performed for six Eastern Canadian clay deposits. Specific correlations were established between normalized shear wave velocities, V_s1, with the overconsolidation (OCR) and void ratios (e). The paper examines the applicability of existing correlations by comparing V_s1 values obtained from P-RAT correlations to those predicted by published laboratory correlations. While several correlations can be used to predict V_s for Eastern Canadian clay, the applicability of other correlations has however been questioned. The analysis reveals the importance of considering the effect of the percentage of fine particles (<2 μm). This effect changes the void ratio variation range, which in turn has a significant impact on V_s values. Furthermore, two general correlations are suggested based on P-RAT results and considering the clay content of analyzed sites. These general correlations can be readily used to estimate V_s1 values for low and high plasticity clays.