ABSTRACT
The results of field and laboratory investigations on two test sites located on organic soils in northwestern Poland are presented. Comprehensive investigations comprising observations at four test embankments and laboratory investigations were carried out to study the behaviour of consolidation process in organic subsoil. It was shown that large deformations, both vertically and horizontally occur during and after construction period. Due to this foundations of embankments on soft organic soils involves subsoil improvement prior to construction. One of the improvement methods is preloading with the application of vertical drains to accelerate the consolidation process. The observations of organic subsoil behaviour show that vertical strip drains may effectively improve the bearing capacity of amorphous peat and gyttja for stage-constructed embankments. Moreover, it was shown that there is a significant difference in pore pressure distribution under embankments with and without vertical drains. As a result of the vertical drain installation under part of slopes, a significant decrease in the horizontal displacements took place.
