A newly developed friction-interlocking armor unit called the ‘Double cube’ (DC) was designed to improve the performance of a concrete armor unit used in river/marine structures against currents/waves actions. The DC unit is an octagonal-shaped block made up of two parts: an upper cube set on a lower base that is either square or octagonal in shape. The innovative design aims to provide good performance in terms of stability, to allow for high tolerance placement with various contact points, and to allow for ease of placement. The DC’s shape and placement enhance the unit’s stability by bringing the center of gravity closer to the underlayer and by providing a large contact surface with the surrounding blocks that reduces the chance of extraction and limits movements (rocking, lifting) via the “keystone” effect. The characteristics of this new unit provide a relatively high hydraulic stability number for the armor layer (NS = 2.9), a favorable hydraulic performance due to energy dissipation from turbulence and aeration, as well as a high roughness coefficient (γf ≈ 0.46), helping to reduce overtopping.

The newly developed friction-interlocking armor unit, called ‘Double cube’ (DC), has been designed to improve the performance of the concrete armor unit used in river/marine structures against currents/waves actions. DC unit, is an octagonal-shaped block, made up of two parts: an upper cube set on a lower base that is either square or octagonal in shape. The innovative design aims to provide a good performance in terms of stability, high tolerance placement with various contact points and ease of placement. DC’s shape and placement enhance the stability by bringing the center of gravity closer to the underlayer and providing a large contact surfaces with surrounding blocks that reduce the chance of extraction and limit movements (rocking, lifting) via "keystone" effect. The characteristics of this new unit provides a relatively high hydraulic stability number for the armor layer (NS=2.9), a favorable hydraulic performance due to energy dissipation from turbulence and aeration, as well as a high roughness coefficient (γf≈0.46) helping to reduce the overtopping.

Abstract:Compact artificial units with protrusions (such as Accropod™II or Xbloc ® ) are used in rubble mound breakwaters for their efficiency in extreme wave events. Recent research studies on such kind of units (Starbloc ® ) have focused on fluid processes close to the armour layer related its roughness, permeability and stability. Lessons drawn for the resulting knowledge of these research works have led to design a new armour unit offering stability, controlled run-up and easy placement. In this paper, 2D hydraulic stability tests are discussed.

RésuméL'implantation d'éoliennes en mer nécessite de connaître les conditions de stabilité des supports de ces structures face aux forces exercées par la houle. Les résultats que nous présentons ici portent sur l'analyse de la condition de non basculement d'une structure support, de concept Seaflower (SAIPEM) avec caissons gravitaires. Or les formules classiques définies pour des cylindres horizontaux de section uniforme, ne conviennent pas à ce type de structures constituées d'éléments cylindriques verticaux. Dans notre analyse nous avons dissocié les efforts exercés par la houle sur différents types d'embases gravitaires à ceux exercés sur la structure complète. Nos premiers résultats ont permis de proposer des solutions d'optimisation des embases gravitaires et de quantifier l'influence du mât. AbstractInstallation of offshore windmill requires to understand stability conditions against wave load. The formulation of Morison is traditionally used to described the total load for fixed cylinder (Hald 2002). However this relation is recognized as not fit well to the study of vertical cylinder almost if this one is made up. In the analysis of the stability we studied the inversion of structures according to the Seaflower concept (Saipem) with gravity boxes. These first results to the measure of the torque reaction, enabled us to optimize the concept and to give a solution more stable for that kind of gravity structure.

The newly developed friction-interlocking armor unit, called ‘Double cube’ (DC), has been designed to improve the performance of the concrete armor unit used in river/marine structures against currents/waves actions. DC unit, is an octagonal-shaped block, made up of two parts: an upper cube set on a lower base that is either square or octagonal in shape. The innovative design aims to provide a good performance in terms of stability, high tolerance placement with various contact points and ease of placement. DC’s shape and placement enhance the stability by bringing the center of gravity closer to the underlayer and providing a large contact surfaces with surrounding blocks that reduce the chance of extraction and limit movements (rocking, lifting) via "keystone" effect. The characteristics of this new unit provides a relatively high hydraulic stability number for the armor layer (NS=2.9), a favorable hydraulic performance due to energy dissipation from turbulence and aeration, as well as a high roughness coefficient (γf≈0.46) helping to reduce the overtopping.