Semianalytical Solution for Pile Installation Response in Marine Soft Clays Considering Anisotropy and Structural Degradation

The penetration of piles into marine soft clays causes significant soil disturbance, resulting in substantial changes to effective stress, pore-water pressure, and soil structure. This study presents a semianalytical framework to address the pile penetration problem using the strain path method (SPM). The soil's stress–strain behavior is described by the ANICREEP model, which accounts for inherent anisotropy, destructuration effects, and strain-rate dependency in marine soft clays. By integrating the ANICREEP model within the SPM framework, the governing equations are expressed as ordinary differential equations to the pile tip advancement. The proposed solution is validated by comparing it with an established cavity expansion solution. Key aspects such as stress evolution, excess pore pressure response, and changes in fabric anisotropy in the surrounding soil are examined to explore the effects of pile penetration. Research findings show that at the pile–soil interface, the SPM predicts lower radial effective stress and excess pore pressure than the cavity expansion method (CEM). In contrast, it yields higher vertical and circumferential effective stresses. Importantly, the SPM accounts for vertical shear stress in its formulation—a key factor that the CEM overlooks. Parametric analyses indicate that the initial bonding parameter significantly influences postinstallation stress distributions, while the impact of the penetration rate is relatively minor. Additionally, the pile installation process modifies the inherent anisotropic properties of the surrounding soil, inducing rotational hardening that critically influences the subsequent reconfiguration of the stress field.