CHAPTER 7 STRUCTURAL DESIGN OF BREAKWATERS Breakwaters are built for several reasons, one of those reasons are for determination of the harbor’s water area, and to protect this area from the impact of the waves in order to protect the ships inside the harbor from the action of these waves, especially during anchorage of these ships for loading and unloading. Also breakwaters are built to protect natural protected harbor entrances or navigational channels from the effect of wave impacts during their entrance (or exit), as well as the reduction of the amount of dredging needed in navigational channels and harbor entrances. Breakwaters can be built also for shore protection and to create calm areas for swimmers in recreational areas. The following factors are taken into account in the planning of breakwaters 1. Breakwaters planning should lead to allowable wave heights within harbor water areas that should be protected. 2. Breakwaters planning should not lead to creating water currents that can cause difficulties in navigation through navigational channels or harbor entrances 3. Breakwaters planning should not lead to erosion or accretion on either side of port locations - or at breakwater’s location. These locations may require additional artificial protection to prevent the occurrence of this phenomenon. 4. Breakwaters planning should not result in entrance of currents loaded with sediments to the port’s water area that could lead to sedimentation, and thus reduce designed water depths. These accretions may require a lot of expensive dredging works, as well as to obstruction in ship maneuvers within the port. 5. As breakwaters are one of the most expensive construction works, planning must be designed to achieve economic costs by designing economic breakwater lengths and breakwater sections without affecting the safety of breakwaters or the efficiency of the water area. 6. Planning of breakwaters is accompanied by the use of refraction and diffraction diagrams to assure the safeness of the protected harbor water area from the effect of dangerous waves.
Structural Design of Breakwaters Chapter 7 CEI 451 Harbor, Navigation and Shore Engineering Dr. Hesham N. Farres 2 Types of breakwaters Breakwaters can be divided according to terms of construction and to how these breakwaters prevent waves from entering the water area through the following types: - 1- Fixed breakwaters a) Inclined breakwaters usually called rubble-mound breakwaters b) Upright breakwaters c) Composite breakwaters 2- Mobile breakwaters a) Floating Breakwater b) Hydraulic Breakwater c) Pneumatic Breakwater Rubble mound breakwaters consist of piles of rocks or stones that can consist of natural or artificial concrete stones or both. Side slopes and stones’ weights are determined such that they do not move from their positions under the influence of waves. As a result of the inclination of these types of breakwaters in front of incident waves; water depths gradually decrease over these slopes that help in breaking of the attacking waves.
- Winter '13
- ayman zakaria
- Physical oceanography, breakwaters, Dr. Hesham N., Hesham N. Farres