Prediction and Control of Settlement for Super-Large Underwater Caisson Foundations Based on Numerical Simulation

Aiming at the settlement control challenges faced in the construction of super-large underwater caisson foundations for the Saudi THE RIG offshore platform project, this study integrates multidisciplinary theories from ocean engineering, geotechnical engineering, and computational science to conduct research on settlement prediction and control techniques. The results show that the settlement of the subsoil decreases progressively from top to bottom, and the compression range extends beyond the foundation area of the caisson, indicating load diffusion within the subsoil. The numerical simulation results are 3% higher than those obtained from theoretical calculations, demonstrating the feasibility of using numerical analysis to predict the settlement of caisson foundations. Because the rubble bed has a thickness of only 1 m, adjusting its mechanical parameters has a limited effect on settlement control; increasing its thickness is beneficial to settlement reduction. Deep cement mixing piles can significantly control settlement, and both higher replacement ratios and greater reinforcement depths improve effectiveness, though the reinforcement range should not exceed the caisson foundation footprint. The findings of this study not only provide theoretical and technical support for settlement prediction and control of the THE RIG project but also serve as a reference for design optimization and construction of similar large-scale marine foundations.