ABSTRACT
The soil improvement through the technique of preloading associated with vertical drains was used to accelerate the consolidation process and reduce the post-construction settlements of the foundation soil of two cylindrical oil tanks founded on alluvial deposit. A summary of the work sequence is provided together with the main aspects of site investigation and geotechnical characterization. An extensive field monitoring of the site was carried out during the embankment construction, the preloading period and, after the embankment removal, during the hydraulic leakage test of the tanks. Differential settlements and angular distortions of the tank foundation evaluated from the measured settlement profiles were compared with expected profile shapes for tanks overlying homogeneous compressible soil layers. Observed absolute and differential settlements and distortions are consistent with the allowable limits provided by the literature and with the design prescriptions, thus confirming the effectiveness of the preloading and drainage technique adopted in the project.
