Studies on the Erosion of a Compacted Soil

by G. J. Hanson, (M.ASCE),
K. M. Robinson, (A.M.ASCE),

Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water


In the management of water there are certain applications in which compacted soil is used (i.e., dams, embankments, levees, spiliways, and channels). Engineers rely primarily on field measured water content (wc%) and dry unit weight (γd) to verify proper compaction of soil. This approach evolved from the practice for structural fills for which strength and compressibility are of primary concern. In water management the erosion resistance of the compacted soil is also an engineering concern. In this paper a submerged jet testing apparatus and procedure are used to measure and compare the erosion resistance of a soil prepared in the laboratory and in the field at varied wc% and γd. The basic premise is that erosion of a material is dependent on the hydraulic stress applied and the resistance of the material. A jet index, J1 is determined from the tests, indicating erosion resistance. A jet index greater than 0.015, between 0.005 and 0.015, and less than 0.0005 are nonresistant, moderately resistant, and resistant respectively. Equations to predict J based on laboratory prepared samples tested in the prewetted state and at the prepared wc% state are developed. Both equations tend to be upper bounds for samples tested from the constructed fill. The results from the fill tests indicate that at the compaction energy level used in construction, a wc% of approximately 15% would be required to be consistently resistant to erosion. The optimum wc% for this compaction energy and soil appeared to be 14–15%. Therefore, in order to achieve consistently erosion resistant material, a compaction wc% greater than optimum would be required for this compaction energy.

Subject Headings: Compacted soils | Load and resistance factor design | Compaction (material) | Soil water | Fills | Erosion | Embankment dams | Field tests

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