A series of centrifuge tests has been carried out to investigate the behaviour of dikes under uplift conditions. Particular attention is paid to clay dikes that are founded on a permeable layer of sand. A rising water level in the river causes an overburden pore water pressure beneath the clay layer, resulting in a reduction of friction between the sand and the clay layer, which can lead to failure of the dike. A test set-up is developed to model a complete system including riverbed and hydraulic gradient in the sand layer. Points of research are the determination of length and location of the uplift zone and the influence of material and geometrical parameters. Special attention is paid to groundwater flow by adapting the sand layer. The effects of a berm and a ditch are studied as well. A comparison is made between the centrifuge tests and analytical and numerical calculations using a finite element program.
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