Behaviors of dynamic modulus and damping ratio of loess in Gannan region of Gansu Province

The dynamic constitutive relation of redeposited loess in Gannan region is investigated based on the dynamic triaxial tests. The model parameters are obtained, and the behaviors of dynamic shear modulus ratio and damping ratio are analyzed. The attenuation model for the dynamic shear modulus and the growth model for the damping ratio with dynamic shear strain are provided. Moreover, the differences about the shear modulus ratio and damping ratio between redeposited loess and eolian loess are discussed depending on the normalization processing and comparison of model parameters. The results show that the dynamic constitutive relation of redeposited loess obeys the hyperbolic model, and the value of model parameter a has no obvious difference with that of the eolian loess, but the value of b is 1.5 times that to 3 times that of the eolian loess under the same condition. The original dynamic elasticity modulus E_dmax of redeposited loess is greatly influenced by the consolidation condition and the loess density, and under the same condition, the value E_dmax of residual loess is smaller than that of alluvia loess. The dynamic shear modulus ratio of redeposited loess decreases with the increase of dynamic shear strain, and the variation trend of shear modulus ratio presents a tendency of negative exponential attenuation model. The trend of D ~γ_d obeys the logarithmic relationship which increases with the increase of dynamic shear strain. Compared with that of the eolian loess, the attenuation rate of the dynamic shear modulus of the redeposited loess is more quickly, and the increase range of the damping ratio is relatively narrow, which indicates the obvious influences of sedimentary environment on the differences of dynamic properties of loess.