Settlement Analysis of Gravity Wharf on Spatially Variable Foundation under Consolidation–Creep Coupling Conditions

The risk of excessive settlement in marine clay foundations has long been a concern in engineering practice, stemming from clay creep and spatial variability in foundation design. The core challenge lies in the time–space mismatched coupling of consolidation and creep in laboratory tests, while large-scale long-term in-situ measurements are impractical. To tackle long-term settlement evaluation for spatially variable foundations under consolidation–creep coupling, this study innovatively proposes a framework of “element test decoupling–analytical calculation–equivalent modulus recoupling”: laboratory tests statistically analyze marine clay properties to decouple consolidation and creep parameters; settlement is calculated via the analytical solution based on two hypotheses A/B; and consolidation–creep recoupling is achieved using the random finite-element method with an equivalent modulus. This study examines the long-term, time-varying patterns of the mean and coefficient of variation (COV) of the soil compression modulus, investigates the effects of the COV and correlation distance of the foundation compression modulus on settlement, and proposes settlement adjustment coefficients that account for both consolidation–creep and spatial variability. Results show that both the mean and COV of the soil compression modulus exhibit significant attenuation over time. For the studied cases, taking the 100-year (100 a) settlement as the criterion, Hypothesis A underestimates settlement by 43.9% relative to Hypothesis B, and foundation spatial variability further increases the mean settlement to 1.01–1.09 times that of the deterministic settlement result under Hypothesis B. The corresponding adjustment coefficients range from 1.46 to 1.77 for Hypothesis A and 1.02 to 1.23 for Hypothesis B. This study provides a quantitative basis and innovative theoretical support for settlement calculation and engineering design of spatially variable foundations.