This article compares and analyses the behaviour of three test embankments. The soil foundation consisted of
normally consolidated clay overlain by a thick sand surface layer. The embankments were rapidly constructed until failure,
which occurred after approximately 50 days. Two of the embankments were reinforced, one including prefabricated
vertical drains (PVD), while the third had neither reinforcement nor PVDs. The two reinforced embankments presented
similar net embankment heights (fill thickness minus average settlement) at failure, owing to the similarity in the undrained
strength values of the two clay layers. The test embankment with PVDs showed that this drainage feature improved overall
behaviour but the benefit was less than suggested in the literature, owing to the low coefficient of consolidation of the
normally consolidated clay, rapid construction and drain disturbance effects. Numerical analyses of the test embankment
with PVDs showed good overall agreement between measured and computed values and confirmed overall field
observations. The embankment without reinforcement and PVDs reached a greater embankment height than the two
reinforced embankments, owing to its greater clay strength.
