Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/28066
Title: Experimental Evaluation of Kovács’ Equations for Estimating Critical Gradients
Authors: Montalvo-Bartolomei, Axel K.
Robbins, Bryant A.
Murphy, John W.
Keywords: Backward erosion piping
Laboratory testing
Erosion--Mathematical models
Internal erosion
Dams
Levees
Hydrogeology
Soil mechanics
Slopes (soil mechanics)
Piping – Erosion
Numerical analysis
Publisher: Geotechnical and Structures Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical Report (Engineer Research and Development Center (U.S.)) ; no.ERDC/GSL TR-18-16
Abstract: Kovács (1981) presented two equations for the critical hydraulic gradient required to cause particle movement on slopes of cohesionless soils. One assumes a sliding failure mechanism due to movements parallel to the slope; the other assumes a heave mechanism due to grain movements normal to the slope. The use of these equations has been proposed for the prediction of piping initiation on slopes. The objective of this investigation was to evaluate through laboratory experiments and numerical analysis the reliability of using Kovács’ equations to predict the gradients required for initiation of backwards erosion piping (BEP). Two sands at three slope angles were tested in a custom-made flume. Results showed that BEP initiation occurs over an incredibly small length. Kovács’ formulation based on sliding was found to be overly sensitive to slope angle and did not match experimental observations. Kovács’ heave-based formulation closely matched the experimental observations, indicating that initiation of BEP is a heave-type failure. While the heave-based equation aligned with the experiments, the length over which the gradient must be examined is too small to be of practical use in field applications and should not be relied upon as a predictive tool for BEP initiation.
Description: Technical Report
Gov't Doc #: ERDC/GSL TR-18-16
Rights: Approved for public release; distribution is unlimited
URI: http://hdl.handle.net/11681/28066
http://dx.doi.org/10.21079/11681/28066
Size: 69 pages / 16.36Mb
Types of Materials: PDF/A
Appears in Collections:Technical Report

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