Structural Failure of the Cohesive Core of Rockfill Dams: An Experimental Research Using Sand-Bentonite Mixtures

This article presents experimental research focusing on the structural failure of the central core of a rockfill dam using sand-bentonite mixtures. It comprised an extensive geotechnical characterization of soil materials and mixtures, including compaction and strength tests, as well as the construction of 1 m high and 1.5 m wide physical models. The displacements of the cohesive cores were recorded using a tailored measuring system, based on a laser pointer and a mirror, designed to amplify the real displacements. The cohesive cores were extremely sensitive to small oscillations and behaved as rigid bodies, similar to concrete slabs with three fixed sides and another free. The shape and dimensions of the breach formed on the cohesive cores had roughly the same shape and dimensions as the unprotected area. This experimental research has the potential to be used as validation tool for several models available in the literature to predict the failure of embankment dams.