Predicting normalized shear modulus and material damping ratio curves of marine clays

A database was developed of resonant column tests to characterize the shear modulus (G) and material damping ratio (D) at small shear strains (10-5 % to about 0.1 %), and strain-controlled cyclic direct simple shear tests to evaluate the decrease of G and the increase of D at large shear strains (0.1 % to about 10.0 %) performed on clays from the Bay of Campeche with carbonate content between 0 % and 100 %, retrieved from seafloor to 120 m below seafloor. The database was tailored specifically to develop numerical modeling to predict the variation of normalized shear modulus (G/Gmax) and material damping ratio as a function of shear strains (γ) when dynamic test results are unavailable for all the clay layers. The equations developed to calculate the curves of G/Gmax-γ and D-γ of Bay of Campeche clays are recommended for preliminary or perhaps even final seismic site response evaluations.