Please use this identifier to cite or link to this item:
Title: Scale effect tests for rubble-mound breakwaters; hydraulic model investigation
Authors: Dai, Yin Ben.
Kamel, Adel M.
Keywords: Breakwaters
Hydraulic models
Rubble-mound breakwaters
Scale effects
Breakwater stability
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Research report (U.S. Army Engineer Waterways Experiment Station) ; H-69-2.
Description: Research Report
Abstract: Laboratory investigations conducted by and for the Waterways Experiment Station under ES 815 , "Stability of Rubble-Mound Breakwaters," determined the relative importance of the different variables with respect to the stability of rubble-mound breakwaters and formulated design criteria for those structures. In ES 815, test-wave dimensions, water depth, and the armor-unit sizes used corresponded to a model with a linear scale of about 1:50 for a prototype structure with rock armor units of about 20 tons. In order to determine the effects of model scale on the results obtained in the ES 815 and similar studies, the ES 847 tests were conducted duplicating the ES 815 testing techniques using model scales of 7.5:1, 1:1, and 0.5:1 relative to the linear dimensions of the ES 815 scale tests . The breakwater test sections used had primary cover layers composed of smooth or rough quarrystones or quadripod armor units . The ES 847 investigation included : (A.) tests for the selection of the maximum no-damage wave heights for the condition of no overtopping, (B.) damage tests to determine the amount of damage to test sections when they were attacked by waves with heights about 1.6 times their maximum no-damage wave heights, and (C.) determinations of wave runup and rundown on the breakwater slopes tested. Test results indicated that, for the type of breakwater sections and armor units tested, no significant scale effect in the selected no-damage wave heights was present for models with scales of 7.5:1 and 1:1; however, a significant scale effect was found to occur for the tests of the 0.5:1-scale model. This scale effect is believed to have been due to the smallness of the 0.5:1 model, which caused the viscous forces to be significant and thus result in inaccuracy in model results. Results of damage and wave runup and rundown tests for the three models did not follow any trend that would indicate the existence or nonexistence of scale effect. It was concluded that no scale factor would be required when applying the results of ES 815 and similar tests to the design of full-scale breakwaters when the Reynolds number, as defined in this report, is equal to or greater than about 3 x 10⁴.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Research Report

Files in This Item:
File Description SizeFormat 
RR-H-69-2.pdf9.57 MBAdobe PDFThumbnail