Quasi-static Loading Effects on a Mar shalling Yard Calibration of a Creep-SCLAY1S Model Using Satellite and In Situ Measurements

Sammanfattning

Marshalling yards on soft clay deposits are subject to long-term settlements drivenby consolidation and creep, posing challenges for track geometry maintenance andoperational reliability. This thesis investigates time-dependent settlement behaviourat Sävenäs marshalling yard in Gothenburg, Sweden, through numerical modellingusing the Creep-SCLAY1S constitutive model in PLAXIS 2D. The model accountsfor anisotropy, bonding and rate-dependent deformation, making it well suited forthe soft Gothenburg clay conditions at the site. Model parameters were calibratedusing site-specific oedometer and triaxial test data, supplemented by theoreticalrelationships and literature values for similar Scandinavian clay deposits. The calibrated model was validated against two independent field datasets: bellow hosemeasurements tracking subsurface deformation at multiple depths, and surface settlement rates derived from Sentinel-1 InSAR observations. Good agreement wasachieved at most monitoring locations, with simulated long-term settlement ratesof approximately 4–5 mm/year consistent with satellite observations. The variability observed in InSAR data within the depot area is interpreted as reflecting cyclicvertical movements from operational loading rather than measurement noise. Operational loading was represented using a quasi-static approach, where train loads wereactivated and deactivated over time according to track occupancy patterns. The results show that excess pore pressure and settlements are most pronounced in theupper soil layers, with the influence of loading diminishing clearly with depth. Partial pore pressure dissipation between load cycles prevented progressive settlementacceleration, and the response approached a stable long-term condition consistentwith partially drained behaviour. For preliminary assessments, a simplified constant load of approximately 50% of the full load was found to produce comparableresults to the quasi-static scheme if only settlements in the clay is of interest. Thestudy demonstrates that advanced constitutive modelling combined with remotesensing validation provides a reliable framework for assessing long-term settlementbehaviour in railway infrastructure on soft clay.