Accurately predicting pile penetration in marine soft clays is crucial for effective construction, load-bearing design, and maintenance of offshore pile foundations. A semi-analytical solution employing the combined expansion-shearing method (CESM) is introduced to model pile penetration in soft clays. This method innovatively simplifies the Pile penetration into undrained cavity expansion and vertical shearing. Using the S-CLAY1S model, which incorporates the anisotropy and structure of natural soft clays, an exact semi-analytical solution was developed to describe soil behavior around the pile under undrained vertical shearing, expanding upon existing undrained cavity expansion solutions. The accuracy and innovation of the CESM were validated through the results of field tests and finite element simulations. Additionally, a comprehensive parametric study highlighted the significant impact of soil's initial structure and stress state on pile penetration response. The study findings strongly align with theoretical calculations, field Measurements, and numerical simulations. Compared to the conventional cavity expansion method, CESM excels in resolving soil stresses at the pile shaft, albeit with a slight limitation in evaluating excess pore water pressure of soils at the pile shaft. The proposed solution considers the fundamental properties of soft clays, including their anisotropy and structural behavior, while incorporating the vertical shearing experienced by the soil during pile installation, thereby providing a simplified yet precise theoretical framework for addressing pile penetration challenges.

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 study introduces a novel methodology to address consolidation under long-term cyclic loading. The approach simplifies analysis by neglecting cyclic load induced fluctuations and by decomposing the cyclic load into a static load and a vibratory load without net tensile or compressive tendency over time. One-dimensional vibration consolidation tests are proposed to investigate the consolidation behavior of normally consolidated soil under vibratory loading. These tests yield a normal vibration consolidation line, which visually represents the consolidation effect of a given vibratory load on normally consolidated soil under different consolidation pressures. Based on these test results, a mathematical model is developed. This model incorporates a constitutive relationship that accounts for both the decrease in effective stress due to the structural damage caused by the vibratory load and the increase in effective stress due to the compression of the soil skeleton. The governing equation, with void ratio and effective stress as dependent variables, comprehensively describes the state change process of soil elements during vibration consolidation. Numerical solutions are then employed to analyze this process in detail.

Soft clays exhibit significant challenges in geotechnical engineering due to their low permeability, high compressibility, and susceptibility to settlement under applied loads. These geological factors pose unique difficulties in predicting long-term settlement accurately and efficiently, particularly through Class C prediction methods that involve iterative processes with complex numerical models. To address these challenges, this study presents an efficient approach for Class C prediction of long-term settlement in soft clays. This approach integrates Bayesian updating with structural reliability methods (BUS) and the general simplified Hypothesis B method which is a semi-analytical method based on one-dimensional elastic visco-plastic (1D EVP) model. Unlike previous research that used Response Surface Model (RSM) with polynomial function for consolidation evaluation, the proposed approach enhances both accuracy and performance consistency under varying conditions. Additionally, by leveraging analytical solutions instead of iterative small-time steps required by Finite Element Method (FEM) or Finite Difference Method (FDM), the computational efficiency is also enhanced. The effectiveness of the proposed approach is demonstrated through its application to an embankment improved with prefabricated vertical drain (PVD) in Ballina, New South Wales, Australia. Comparative analyses demonstrate that the predicted settlements from this study, using only the monitoring settlement data collected prior to the 76th day of the project, align closely with the results from established RSM and FEM-based Bayesian back analysis approaches. The obtained results also indicate that the predicted settlements, based on 76 days of monitoring data, closely match field measurements at various depths, whether relying solely on settlement data or integrating additional pore water pressure data. For the Ballina embankment, over 40,000 consolidation analyses required for a single BUS simulation can be completed within 10 h using the general simplified Hypothesis B method, compared to months it might take with FEM or FDM approaches. This makes the proposed approach a practical tool for geotechnical engineers, enabling reliable settlement predictions early in the project timeline while maintaining low computational costs.