Shear wave velocity-based assessment of liquefaction resistance of carbonate sands

Owing to some peculiar properties of “unusual” calcareous sands, most of which is linked to grain crushability, an accurate evaluation of liquefaction resistance (CRR) of such sediments requires the development of new soil-type specific relationships. An experimental laboratory study based on undrained cyclic simple shear (SS) tests and bender element (BE) tests in triaxial apparatus was performed on a biogenic uncemented carbonate sand, Quiou sand, dug out from a site close to Plouasne (Brittany region, France), in order to seek a relationship between CRR and normalized shear wave velocity (Vs1). Sand specimens were reconstituted for a range of relative densities varying between 30% and 85% by water sedimentation method. The influence of factors affecting Vs and CRR measurements, such as initial void ratio, effective confining stress and reconstitution method were investigated and discussed. The results obtained in the present research together with those of previous studies evidence that the liquefaction resistance of carbonate sands is lower than that predicted by the field-based curves drawn for corresponding silica sands.