Compaction in lab-scale experimental studies of earthen embankment breaching

Abstract

The breaching phenomenon largely depends on compaction of embankment material as it offers resistance to erosion. Consistency in compaction is crucial in earthen embankment breaching experiments to acquire meaningful results and inferences. However, this critical factor is generally neglected in the construction of earthen embankment models in the reported studies. Studies often assume that keeping the water content equal to optimum and compacting each layer of embankment with an equal but arbitrary number of passes of rammer or roller ensures equal compaction, regardless of embankment height and material. However, this assumption does not hold because material properties and embankment height affect compaction. The inconsistent compaction levels so achieved will influence the results of embankment failure experiments, leading to erroneous inferences and conclusions. This paper proposes a novel approach to achieve consistent compaction in laboratory embankment models of varying materials and heights. In the present work, the laboratory embankments are compacted at the optimum water content (ωopt) using the number of blows of a rammer that impart the same compaction energy to the embankment as that of the standard compaction test. The methodology is illustrated through a sample calculation. All the embankment models constructed using the proposed approach achieved more than 90% compaction, satisfying the criteria of embankment construction in practice. This consistent level of compaction achieved across embankments of varying materials and heights allows for reliable comparisons of results in subsequent embankment breaching experiments. The researchers conducting experiments involving embankments will find the results of this study useful.