engleski

The State of the Rubble Mound Breakwaters Primary Cover Layer in Istria

The paper addresses the field investigation conducted to define the condition of the primary cover layer of six Adriatic rubble mound breakwaters on the western shore of Istria. A few characteristic profiles were observed on each breakwater, 3, 5m wide from the crest downwards to the sea level line on the slope. The dimensions (mass), as well as interlocking blocks were measured by means of a mutual contacts number. The granulometric curve of each profile’s primary cover layer was defined basing on the recorded data. The real value of Hudson’s layer coefficient KD was estimated on the basis of contact statistics and transformed Hudson’s equa-tion. The significant wave height in front of breakwater (i.e. in shallow water) defining the breakwater’s stability was determined for each location according to the Hudson’s equation, with the known mass of 50% represented block, and estimated value of the layer coefficient KD. The shallow waters’ wave height obtained in this way, considering the wave deformations, was transformed into equivalent deep sea waters’ wave height by the calculation of shoaling and backward refraction. The wave return periods resisted by the mentioned breakwaters were obtained by inputting wave height, defined in above mentioned way, into self-developed maps of long term wave climate for the Adriatic.

rubble mound breakwater, primary cover layer, field investigation, primary cover layer stability

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