Strain-rate dependent behaviors of K₀ consolidated clays

Based on the newly developed anisotropic elastic visco-plastic constitutive model for K0 consolidated clays,the expressions of preconsolidation pressure and undrained triaxial shear strength were presented,and their strain-rate dependencies were investigated.The strain rate parameter of undrained shear strength was a constant which just depends on the ratio of the consoliation coefficient to the secondary compression index,but the corresponding parameter of preconsolidation pressure was dependent on this ratio as well as the compression parameter Λ.For most inorganic clays,the preconsolidation pressure and undrained strength would increase by 8%²1.2% and 7.2%¹2.2% respectively with a tenfold increase in the strain rate.Considering the differences of strain rate between the laboratory test and the field condition,it is suggested that the measured preconsolidation pressure and undrained strength should be modified before applied to the in-situ condition.As OCR increases,the increasing rate of the strength ratio with strain rate becomes faster.