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Title: Damage progression on rubble-mound breakwaters
Authors: Melby, Jeffrey A.
Keywords: Armor
Life-cycle costs
Rubble mound
Publisher: Coastal and Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CHL-99-17.
Description: Technical report
This report addresses depth-limited breaking-wave damage on rubble-mound breakwaters. Few generalized studies have been conducted on this topic; so no engineering methods exist for determining deterioration rates of breakwaters exposed to sequences of storms. A new experiment is discussed measuring incipient motion on both stone and sphere armor layers. An incipient motion criterion is derived for the dominant mode of motion: vertical lift under the steep breaking-wave face. Previous breakwater damage experiments and measurement techniques are thoroughly reviewed. A new experiment is described consisting of seven relatively long-duration breakwater damage test series. The test series were conducted in a flume using irregular waves. Wave height, wave period, water depth, storm duration, storm sequencing, and stone gradation were varied systematically. The experiment yielded relationships for both temporal and spatial damage development. Maximum eroded depth, maximum eroded length, and minimum remaining cover depth are introduced to describe the damaged profile. The mean and standard deviation of these profile parameters are shown to be a function of mean eroded area. An equation is also provided to predict the standard deviation of eroded area as a function of mean damage. Relations for predicting temporal variations of mean eroded area with wave height and period varying with time in steps are shown to describe damage reasonably well.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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