This study investigates the strain development of saturated silty soil of Yellow River under varying initial consolidation inclination angles ζ by principle stress rotation tests. The results revealed that distinct patterns in axial, circumferential and torsional shear strains show the influence of ζ on the mechanical response of silty soil. Notably, the axial strain exhibits compressive behaviour at ζ=90° during the first cycle, while the circumferential strain displays tensile behaviour. Anisotropy initiates at ζ=90° and around 60° for other ζ angles. Different values of ζ exhibit stabilization trends in strain fluctuations, with ζ=90° and ζ=75° showing intriguing similarities. The case of ζ=45°stands out, with the highest fluctuation and strain amplitude. Torsional shear strain similarities are observed among most ζ angles except for ζ=90° and ζ=60°. Volumetric strain emphasizes the significant impact of consolidation angle inclination on anisotropic characteristics. With the increase of the initial solidification angle, the hysteresis curve shifts to the left, indicating cyclic creep characteristics, with negligible shear strain for the case of ζ=60°. As the cycle period increases, the hysteresis loop contracts, indicating the continuous strengthening and eventual stabilization of shear stiffness. This comprehensive exploration provides valuable insights into the complex behaviour of saturated silty soil under rotational stress conditions, highlighting the role of initial consolidation inclination angles in shaping its mechanical response.

A series of hollow cylinder torsion shear tests were conducted for the silty soil in the Yellow River flood area, considering the effect of drainage shearing with major large principal stress direction. The shear stress-strain behavior as well as the anisotropic characteristics of silty soil were investigated. Under different intermediate principal stress coefficients b and major principal stress direction angles α, the stress-strain relationship and the corresponding shear stress ratio of silty soil were obtained. It was concluded that the values of α and b have a significant effect on the octahedral stress-strain and the shear stress-major principal strain. The obvious anisotropicic behavior was observed, especially under b=0.5 or 1.0. Compressed deformation generally occurred in the major principal strain direction. Under a fixed α, the smaller shear strength occurred under a larger b value. The peak shear strength and the corresponding axial strain were the greatest under the conditions of α=45° and b=0.5, relevant with to the highest peak shear stress ratio q_f/p₀.