Critical insights in laboratory shear wave velocity correlations of clays

Abstract


 Shear wave velocity is an important mechanical/dynamic parameter allowing the characterization of a soil in the elastic range (γ < 0.001 %). Thirty five existing laboratory correlations of small strains shear modulus or shear wave velocity were examined in this study and are grouped into different general forms based on their geotechnical properties. A database of 11 eastern Canadian clay deposits was selected and used for the critical insights. The effect of the coefficient of earth pressure at rest was also examined. A range of variation for each general form of correlation was determined to take the plasticity index and void ratio values of investigated sites into account. The analysis shows a significant scatter in normalized shear wave velocity values predicted by existing correlations and raises questions on the applicability of these correlations, especially for eastern Canadian clays. New correlations are proposed for Champlain clays based on laboratory measurement of shear wave velocity using the piezoelectric ring actuator technique, P-RAT, incorporated in consolidation cells. An analysis of P-RAT results reveals the sample disturbance effect and suggests an approach to correct the effect of disturbance on laboratory shear wave velocity measurements. The applicability of the proposed correlations, including the disturbance correction, is validated by comparison with in situ measurements using multi-modal analysis of surface waves (MMASW). 
 

Shear wave velocity—SCPTU correlations for sensitive marine clays

“…Unfortunately, it has been shown that different forms of the correlation equations have been devel oped in different areas. It appears that local correl ations are necessary for satisfactory use of the technique as demonstrated for example by L'Heureux and , Duan et al (2019) or Elbeggo et al (2021). In this paper data for clays in eastern Canada will be examined and compared with similar clays in Norway and southern Sweden.…”

Interpretation Methods for Seismic Downhole Test in Inclined Boreholes

“…The most common seismic geophysical tests performed at the ground surface are seismic refraction and surface wave measurements in multichannel arrays (MASW, SPAC), whereas the tests performed in boreholes are the downhole (DH), cross hole, and uphole tests; the DH test is one of the most commonly used. Conventionally, DH tests are performed in a vertical borehole, where the P-and S-wave travel times are measured from a surface seismic source to a geophone located at different depths within the borehole [4]. Alternatively, DH tests can be performed using a seismic cone penetrometer (SCPT) rig.…”