1.1.This method consists of flowing water over a specimen contained in a tube placed through the bottom of a rectangular cross section pipe as illustrated in Fig. 1. The procedure provides a means of obtaining the site-specific relation between the erosion rate and the mean flow velocity, or the erosion rate and the water-soil interface shear stress of soil specimens. The relation is called the erosion function of the soil and has applications in most engineering works related to soil erosion. The results obtained from this procedure are applicable to both coarse-grained and fine-grained soils. Soft rocks can also be tested with this method. Note 1- Similarly for soft rocks, a rock core sample can be extracted and placed into a Shelby tube for rock erosion testing. 1.2.The principle underlying this method is to collect a specimen from the site where erosion is being investigated and testing the specimen in the laboratory by flowing water over it in a pipe under a pressure flow condition. The sampling tube is placed through the bottom of the rectangular channel where water flows at a constant velocity (Fig. 1). The soil is pushed out of the sampling tube by a piston only as fast as the soil is eroded by the water flowing over it. For each water velocity level, an erosion rate is measured, and a shear stress is calculated using The Moody Chart (Moody, 1944) or a sensor. The conversion from velocity to shear stress using The Moody Chart also require the hydraulic diameter of the pipe, kinematic viscosity, the mass density of the fluid and the average roughness of the specimen surface. 1.3.As a result of this test, a point by point erosion function is obtained for the tested specimen. The erosion function can be plotted as erosion rate-velocity, and erosion rate-shear stress. 1.4.The values stated in SI units are to be regarded as the standard. 1.5.This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
KeywordsEFA; Erosion Function; Scour
This is a revised version of the WK 67195. The document was approved by the subcommittee with 100% affirmative votes. The standard discusses an erosion test apparatus called the Erosion Function Apparatus (EFA). In the early 1990s, the idea of the Erosion Function Apparatus (EFA) was first developed, established, and patented by Briaud at Texas A&M University.Today the EFA is being manufactured by Humboldt, Inc. and used widely by many engineering organizations. This test was originally developed to evaluate the erodibility of a wide range of both cohesive and non-cohesive soils from gravels to clay and silt.
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Draft Under Development