Author(s): M. Luthi; R. G. Millar; R. J. Fannin
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Keywords: Soil erosion; Testing; Piping
Abstract: The Hole Erosion Test (HET) is used to measure the erodibility and critical shear stress of test soils. A soil specimen with a preformed axial hole is subjected to a constant head pressure flow, and the rate of enlargement of the soil pipe is determined indirectly from the flow rate and hydraulic gradient. We have modified the HET by introducing measurement of flow velocity within the pipe using a conventional Pitot-static tube. We conducted a series of tests on non-erodible PVC specimens with axial holes of constant, but different diameters to simulate an enlargement of the pipe. Results further revealed an advanced interpretation of the hydraulic gradient corresponding to head loss assigned to shear stress. A Pitot-static tube for velocity and pressure measurement can easily be incorporated into the HET, and yields more transparent and reliable results by eliminating or amending some of the limiting assumptions of the original test.
Year: 2011