Journal of Waterway, Port, Coastal, and Ocean Engineering

The primary function of composite vertical breakwaters is to shield harbor basins from incoming waves and currents. To ensure high hydraulic efficiency, recurved parapets are commonly employed to mitigate the wave overtopping phenomenon. However, these breakwaters are typically used in locations characterized by high water depth. In such settings, nonbreaking waves form on the seaward side of the structure, leading to a phenomenon known as “Confined-Crest Impact” (referred to as “C-CI” hereafter). This phenomenon arises from the interaction between nonbreaking waves and overhanging structures. As presented in previous research works, the same author showed a method for considering the pressure increment induced by the “C-CI” using empirical relationships. However, these tools were unable to predict pressure increments in the presence of submerged berms. Nevertheless, vertical breakwaters commonly feature a berm designed primarily for seabed leveling. Particularly in areas with deep seabeds, the berm serves the purpose of diminishing the caisson height. The presence of the berm amplifies shoaling effects, leading to an increase in free surface velocity and, consequently, a rise in excess pressure induced by the “C-CI” in the presence of a recurved parapet. For this reason, this research specifically focuses on investigating the influence of the toe berm on “C-CI.” A series of computational fluid dynamics (CFD) numerical simulations have been conducted to analyze how changing the height of the toe berm affects the loading conditions on the recurved parapet. The geometrical configuration of the toe berm has been selected based on the “Parameter Map” outlined in the PROVERBS manual. As a main result, the intensity of “C-CI” tends to increase as the height of the toe berm increases. This is mainly due to the shoaling effect induced by the berm, as the steepness of the waves increases. A new empirical formula has been developed, with the purpose of determining the coefficient required to apply in Goda’s formulas, enabling the estimation of pressure distribution along the structure in presence of berms.

The USACE boasts a navigation portfolio of over 19,312 km (12,000 mi) of shallow draft [from 2.74 m (9 ft) to 4.27 m (14 ft)] inland and intracoastal waterways, 20,921 km (13,000 mi) of deep draft [4.27 m (14 ft) and greater] channels, and 400 ports, harbors, and turning basins. To ensure that these channels remain navigable and at congressionally authorized dimensions, channel maintenance practices are performed annually by dredging. Most of these dredging operations are performed by private companies under contract to the USACE districts. With an abundance of navigation channel maintenance needs and a limited dredging fleet, accurate scheduling and the timely arrival of the dredging fleet is required. Project delays due to production issues, weather delays, contracting issues, or both will generally impact future scheduled projects, navigation, and commerce. Nonawardable bids happen when the contractor(s) proposal(s) are too high compared with the Independent Government Estimate (IGE). These nonawardable bids lead to significant time delays, because the USACE district must then engage in bid verification calls, negotiations, the potential cancellation of the contract solicitation, or both and the subsequent resolicitation for work. Therefore, it is extremely important that USACE cost estimates adequately reflect the level of effort the project requires when capturing all project-associated costs. This paper aims to summarize the USACE conceptual approach to dredge cost estimating by highlighting the complex variables that are associated with this type of estimate.

This article provides a method by which the scour and self-burial of spherical bodies, short cylinders, and truncated cones that are induced by bichromatic and bidirectional waves could be derived. The empirical scour and self-burial depth formulas for spherical bodies, short cylinders, and truncated cones are used with a bed shear stress model beneath bichromatic and bidirectional waves. Examples of the results are given for unidirectional bichromatic and bidirectional monochromatic waves. The results appear to agree qualitatively with physical expectations.