Anisotropic Consolidation Effects on the Dynamic Shear Modulus of Fujian Sand: Experimental Investigation and Predictive Modeling

The dynamic shear modulus of soil is a critical parameter for evaluating the seismic response of geotechnical structures. Although extensive research has been conducted on soil dynamics under isotropic conditions, the understanding of soil behavior under anisotropic stress states, characterized by the consolidation stress ratio ( K c ), remains inconsistent. This study investigates the effects of anisotropic consolidation on the dynamic shear modulus ( G ) of Fujian sand through a series of strain-controlled cyclic triaxial tests, covering a medium-to-high shear strain range. The influences of lateral effective confining pressure ( σ m ), consolidation stress ratio ( K c ), and saturation condition (dry and saturated) on the maximum dynamic shear modulus ( G max ), dynamic shear modulus (G), and normalized dynamic shear modulus ( G/G max ) were systematically investigated under two stress paths: constant σ m and constant mean effective confining pressure ( σ m ′ ). The results indicate that the maximum dynamic shear modulus ( G max ), G , and dynamic shear modulus ratio ( G/G max ) all increase with the increase of σ m . Under two different methods of applying consolidation stress ratio (keeping σ m constant and keeping average effective confining pressure ( σ m ′ ) constant), K c has the same influence pattern on G max , G, and G/G max . When σ m or σ m ′ is kept constant, G max increases with the increase in K c for both dry and saturated sand, with the ratio G max(aniso) / G max(iso) ranging from 1.0 to 1.8. Before γ reaches 10 -4 , the increase in G with increasing K c is significant. However, after γ exceeds 10 -4 , with the increase of γ , higher K c leads to faster attenuation of G. When γ is around 10 -2 , the results of G under different K c values are essentially consistent. On the other hand, G/G max decreases gradually with the increase of K c , and the ratio of reference shear strain