A novel self-sensing spudcan for real-time safety assessment

The real-time assessment of the foundation safety margin for jack-up rig under extreme environmental loads is critical for preventing catastrophic failures. However, direct in-situ measurement of the resultant bearing resistance of the soil-structure system remains a significant challenge. This study develops a novel self-sensing spudcan by embedding Fiber Bragg Grating (FBG) sensors into the spudcan structure, enabling real-time monitoring of its structural strain. Laboratory tests demonstrated a synchronous evolution between the circumferential strain of the spudcan and the mobilised soil resistance. A key finding is that the normalised circumferential strain rate of the spudcan exhibits a strong positive correlation with the foundation safety margin and approaches zero as the foundation reaches its ultimate limit state. Leveraging this correlation, a predictive model that quantifies the safety margin using the measured real-time strain rate was established through numerical analyses, accounting for various loading paths, vertical loads, and soil-structure modulus ratios. The model predictions show less than 13% error compared to experimental data. This work presents a complete solution from smart hardware to an assessment algorithm, providing a robust approach for the real-time safety assessment of spudcan foundations.