NEW DESIGN PRINCIPLES FOR RUBBLE MOUND STRUCTURES

Abstract

This paper describes the effect of wave period on the stability of rubble mound breakwaters. Introductorily wave run-up and run-down on smooth slopes and on rubble mounds were measured, and breaker types were observed and recorded for different incoming wave and slope characteristics. The surf similarity parameter, 5 = , 9° = /-~ - ~^r ' T was found practical for /H/L0 / 2TT /H description of breaker type, run-up and run-down on both smooth and permeable slopes. Pressure measurements along the smooth slopes and in the core of a rubble mound were undertaken with two different core materials. It was shown that the most dangerous condition for the stability of rubble mounds occurs at the so-called "resonance condition". Resonance refers to the situation that occurs when run-down is in a low position and collapsing- plunging wave breaking takes place simultaneously and repeatedly at or close to that location. This corresponds to a range of E, values in between 2 and 3. Photographic instrumentation was introduced and tested to quantify the initial damage on a rubble mound. This paper is a 1/3 abstact of a thesis for the Dr. Eng. degree by Ali Riza Giinbak.