Sensitivity Analysis of Modified Cam-Clay Model Parameters for Energy Piles in Coastal Soft Clay

Geothermal energy piles (GEPs) synergistically integrate structural load-bearing with subsurface heat exchange, yet their deployment in marine soft clay prevalent along China’s eastern coast introduces complex thermo-hydro-mechanical (THM) challenges. Although the Modified Cam-Clay (MCC) model is extensively employed for such soils, regional parameter variability and quantitative sensitivity to energy pile performance remain insufficiently resolved. This study establishes a three-dimensional finite element model using COMSOL Multiphysics and conducts systematic sensitivity analysis by perturbing key MCC parameters (M, λ, and κ) within ±20% and ±40% around benchmark values for Shanghai marine soft clay. Results demonstrate that the compression index λ dominates pile head settlement control, with a ±40% perturbation inducing variations up to 0.7 mm—over five times more sensitive than M or κ—whereas all parameters exhibit negligible influence (<0.5%) on thermal exchange performance. Comparative analysis further reveals significant regional disparities, with Shanghai soft clay showing notably higher λ (0.29) and lower M (0.721) than Fuzhou, Shenzhen, and other coastal regions. Accordingly, for settlement-critical designs, λ should preferentially be determined from high-quality undisturbed sampling. Conservative λ values are to be used where uncertainties remain, laying a rigorous foundation for parameter-testing procedures and safety-factor calibration within GEP design.