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.

This paper presents a novel analytical framework to predict short-term pile setup in natural structure clay, considering the influence of soil destructuration in installation and consolidation. Based on the cavity expansion method, a simulation of pile installation has been conducted, with an analytical solution formulated for cavity expansion under undrained conditions to capture soil destructuration effectively. The flow rate in the unit cell is determined by Darcy's law based on the soil mass volume change, leading to the consolidation equation, which is obtained in a fully analytical form for excess pore water pressure (EPWP) dissipation. The utilization of the average compression curve aimed to depict a partially disturbed state due to the effects of installation. Based on the rewritten effective stress method (beta method), which involves the time-dependent factor while properly incorporating the effects of relaxation and thixotropy by introducing the requisite parameters. Finally, the analytical framework for predicting short-term pile setup is established and validated through a comprehensive pile field test conducted at St-Alban. The close correspondence between the analytical results and the empirical data indicates the effectiveness of the proposed framework in forecasting short-term pile behaviour with reasonable accuracy.

This paper presents a field pile load test program conducted on four 0.36 m closed-end steel pipe piles with lengths ranging between 11 and 13 m installed in fine-grained soils. Subsurface investigations with standard penetration tests and cone penetration tests with pore pressure measurements were performed at the site. Three pushed-in piezometers at incremental offsets from the piles were also installed to monitor pore water pressure changes during and after the installation of piles. Several dynamic load tests were performed at different times to observe the change in pile resistance. A static load test was also performed on one of the piles. Some load test results showed an unexpected decrease in the resistances of some piles with time. The study showed that construction activities, e.g., installation of other piles, disturbs the soil and groundwater conditions which can significantly affect the pile resistance measured during load tests. This investigation revealed that pile driving and restrikes should be scheduled such that the effect of construction activities on load tests results will be avoided or minimized.