Effect of Shape Parameters on Failure of Earthen Embankment due to Overtopping

Abstract

Selection of the appropriate mixtures of earthen embankments plays an important role in reducing the chances of failure of such crucial structures by either overtopping, internal erosion, or seepage, etc. Recent studies show that 34% of failures cases are due to overtopping which pose a major flood risk to the people and properties in the inundation areas. In this study, the failure of compacted homogeneous non-cohesive earthen embankment due to overtopping has been experimentally investigated. Effects of different shape parameters including the embankment downstream slope, the crest width and the height of the embankment on the erosion process are tested. Evolution of the breach shape is tracked using a high-definition camera. Time of failure of the embankments is evaluated for different downstream slopes, crest width and embankment heights. The results show that the downstream slopes have a major effect in changing the failure modes of the embankment. For small downstream slope of 5:1 (V: H), and 10:1, the erosion of the downstream slope takes place along a pivot point located above the bed of the embankment where the base length of the embankment increases by time. However, for higher values, the pivot point is located on the base of the embankment and the base length of the embankment decreases by time till it reaches equilibrium. Also, using different mixtures of gravel/sand materials affect the time of failure.