Placement Test, Porosity, and Randomness of Cube and Cubipod Armor Layers

Abstract

Although little attention is usually given to the armor porosity and armor randomness of randomly placed concrete armor units in mound breakwaters, significant model effects may occur if armor porosity and randomness are different for prototype and small-scale models. Armor randomness and porosity are easier to control in small-scale models because they are generally constructed by hand in dry and perfect viewing conditions; equipment and environmental constraints make control at prototype scale more difficult. Results from three-dimensional small-scale placement tests are analyzed when cube and Cubipod units are placed with a small-scale crawler crane and pressure clamps. Armor porosity was not workable below 37% for cubes and 35% for Cubipods; placement grids were obtained for feasible armor porosities, considering row settlements during construction as well. A methodology to measure armor randomness using high-precision laser scanning, similar to terrestrial LIDAR, was tested with small-scale cube and Cubipod armor. Three armor randomness indexes (ARIs) measured the randomness of cube and Cubipod armor; the values for ARIs were higher for Cubipod armor than for cube armor.