Development of a New Apparatus for the Jet Erosion Test (JET)

The Jet Erosion Test consists of impacting a soil sample with a water jet and analyzing the evolution of the scour depth in order. It was originally designed to assess the resistance of fine soils against overflowing erosion by modelling the headcut migration. To extend this research to the overflowing erosion of mixed coarse – fine soils, EDF and geophyConsult have developed a larger JET apparatus, relying on the hypothesis, which needs to be confirmed, that some mixtures of fine and coarse soils may also have a headcut migration-type overflowing erosion process. A first test campaign has confirmed that JET tests carried out on the same soil with the original Hanson bench and the new apparatus provide comparable results. A second test campaign studied the influence of the nozzle diameter, testing the same soil successively with 6.35, 12 and 20 mm nozzle diameter. The first results confirmed that the results are not significantly influenced by this parameter. A third series of tests were related to soils that contain particles above 4.75 mm. Parallel to this experimental research, the interpretation of the test has been re-analysed, trying to understand the reason for the discrepancies observed between results obtained on French soil tests database and Hanson classification.