Experimental Research on the Dynamic Parameters Characteristics of Coarse Granular Soil Filler for Heavy-Haul Railways

The dynamic characteristics of the railway have important engineering significance for guiding the design and construction of railway subgrades. In this paper, we conducted a large-scale indoor dynamic triaxial experiment for coarse-grained fillers. Through this experiment, the effects of confining pressure, loading frequency as well as other factors on the dynamic parameters (backbone curve, dynamic shear modulus ( G_d) , and damping ratio ( λ) characteristics of coarse granular soil were studied. The results showed that: The varied curve of the dynamic shear stress ( σ_d) and the dynamic shear strain ( γ_d) of the coarse-grained soil satisfies the Hardin hyperbolic model. With an increase in confining pressure and loading frequency, the dynamic shear stress ( σ_d) required to yield the same dynamic shear strain ( γ_d) increases; The dynamic shear modulus ( G_d) of the coarse-grained soil decreases nonlinearly as the dynamic shear strain ( γ_d) increases; furthermore, the dynamic shear modulus increases gradually with the increase of confining pressure and loading frequency; The damping ratio ( λ) of the coarse granular soil increases rapidly first and then stabilizese with the dynamic shear strain ( γ_d) . The damping ratio ( λ) is positively correlated with the confining pressure and the loading frequency. Finally, according tothe test results, the equation of the curve of the damping ratio ( λ) and the dynamic shear strain ( γ_d) is established.