First observations on the internal erodibility of some soil-like weathered rocks by means of Hole Erosion Tests

Concentrated leak erosion involves the initiation and evolution of soil erosion along a pre-existing crack or micro-fissure due to seeping water and it can be often source of severe safety issues in man-made hydraulic infrastructures. In laboratory, this peculiar internal soil erosion mechanism can be simulated using the Hole Erosion Test (HET). The erodibility of highly weathered rock materials is poorly investigated in literature, although these materials often interact with embankment dams or levees. In this study, a series of HET tests were performed on some soil-like weathered rock specimens, coming from a project-site located in Africa, to investigate their susceptibility to develop internal erosion in concentrated leaks. Although affected by a certain degree of variability, the first outcomings have highlighted that some samples are potentially susceptible to be affected by internal erosion with rates from moderately to extremely rapid. The results of this research provide useful insights in the implication of weathering processes in modifying hydraulic properties of rock materials. Eventually, this study testifies that the Hole Erosion Test can be suited to study the progressive erosion of highly decomposed rocks.