Field measurements of the settlements induced by preloading and vertical drains on a clayey deposit

The paper describes the results of an almost two-year long monitoring period of the field performance of the foundation soils of two tanks founded on a clay soil deposit improved using the technique of preloading and vertical drains. During the preloading period settlements were monitored measuring the vertical displacements of settlement platforms by topographic survey. During the hydraulic leakage tests of the tanks their settlements were measured using a level probe along a flexible pipe placed in a shallow excavation under each tank. The measurement results are discussed showing their usefulness in the application of the Asaoka procedure for settlements prediction. Despite the significant influence of the lithological and mechanical heterogeneity of the foundation soils, absolute and differential settlements of the tanks, as well as angular distortions, resulted consistent with allowable limits envisaging a satisfactory performance of the tanks.