Accurately predicting the setup of jacked piles in marine soft clays is crucial for effective construction, load- bearing design, and maintenance of offshore foundations. This paper integrated UMAT subroutines into the ABAQUS platform using two numerical integration methods: the cutting plane algorithm (CPA) and the NewtonRaphson iterative algorithm (NRIA), to simulate the entire life cycle of jacked piles in marine soft clays. The study incorporates the advanced elastoplastic constitutive model (S-CLAY1S) and the elastoviscoplastic constitutive model (ANICREEP), addressing soil fabric anisotropy, structural effects, and, specifically, soil creep effects in the ANICREEP model. A two-dimensional axisymmetric model is established for jacked piles in marine soft clays, involving unloading and consolidation stages, followed by static load tests on test piles at various post- installation rest periods to assess their time-dependent bearing performance. Finite element modeling enables simulations of field and laboratory pile tests, validating models against measurements. Parameter analysis includes variations in excess pore water pressure (EPWP), ultimate skin friction resistance, and pile bearing capacity in both soil models, examining the impact of initial soil structure ratio on pile performance. Key findings reveal differences in EPWP dissipation rates and long-term bearing capacity evolution between elastoplastic and elastoviscoplastic soils, highlighting the ANICREEP model's capability to capture both short-term and creep- induced long-term effects. Integrating complex soil mechanics into ABAQUS enhances the ability to predict and optimize jacked pile performance in various geotechnical engineering applications.

Laboratory model tests were conducted on artificially structured clays using self-developed equipment to better understand the penetration mechanism of jacked piles in structured clays. Two artificially structured clays with the same initial void ratio but different structured strengths, along with one unstructured clay, served as foundation soils for model tests. Cement and salt were selected to simulate the bonding force and macroporous fabric between soil particles in artificially structured clays. The microstructure and mechanical behavior of artificially structured clay samples were analyzed using a scanning electron microscope and a triaxial apparatus. This analysis aimed to evaluate the efficacy of the current method utilized in preparing structured clays and elucidate the evolution mechanism of pile response in structured clays in relation to soil cells. The findings showed that increased confining pressures lead to a more pronounced impact of soil structure on pile jacking force. Unlike the pile shaft, soil structure played a more crucial role in influencing the pile end during jacking, primarily due to the shear-induced structure degradation of clays close to the pile shaft. The axial force and shaft resistance of piles significantly increased with higher cement content. Simultaneously, the mobilization of the increased pile shaft resistance enhanced the nonlinearity in the distribution of axial force along the pile shaft. The pore-water pressure and total radial stress at the pile-soil interface, located 150 mm from the pile toe, experienced respective increases of 1.27 and 1.38 times as the cement content of model soils increased from 0% to 4%.