ABSTRACT
The present work addresses the impacts of the dam’s draining system on the failure by overtopping. It entails the critical assessment of two homogeneous dam breach experiments, with different drainage systems: i) toe drain only and ii) complete draining system.
The analysis of the results includes the comparison of the breach hydrograph and the stages of morphological evolution. Key measurements include 3D breach reconstruction, using a depth sensing device (Kinect sensor).
Major differences in the breaching mechanisms were observed. In test i), once headcuts are formed, the breach enlarges though regressive and undersouring erosion, associated to mass destabilization events. In test ii), headcuts stop deepening once the sand vertical drain is uncovered. The filter erosion evolves strongly inside the dam, leading to the destruction of the downstream slope at relatively small discharges. This configures a major novelty in the conceptual model of dam erosion by overtopping: an erosion stage in which large erosion takes place without significant increase in the breach discharge.
