Experimental Study on the Influence of Sand Content on the Dynamic Characteristics of Remolded Soft Clay

Based on the GDS dynamic triaxial test system, a series of dynamic characteristic tests were conducted on remolded sand-mixed soft clay with varying sand contents to systematically investigate the influence of loading frequency and sand content on plastic cumulative deformation, dynamic shear modulus, and damping ratio. The results indicate that: The development of plastic cumulative deformation exhibits a rapid initial phase followed by a decelerating phase. As the number of vibrations increases, the densification of the soil skeleton inhibits the rate of plastic deformation, while higher sand content significantly amplifies the cumulative deformation. Regardless of whether the loading frequency was below or above 1.0 Hz, the dynamic shear modulus displayed a decreasing trend with increasing sand content. For every 10% increase in sand content, the modulus reduction reached 12%~18%. During vibration, the pore pressure coefficient A continuously increased, intensifying the shear contraction effect and deteriorating soil stability. Higher sand content exacerbated this phenomenon, resulting in distinct inflection points in the dynamic shear modulus and damping ratio curves (critical sand content approximately 20%). In summary, sand content significantly influences the dynamic response mechanisms of sand-mixed soft clay by altering the soil skeleton structure and drainage pathways, providing critical insights for constructing dynamic constitutive models and guiding seismic engineering design.