There are different types of marine structures constructed for various purposes. Construction and uses of these types of marine structures is discussed.
Different materials such as concrete, stone, timber, and steel have been used for construction of marine structure. These structures need to be designed in such a way that can withstand various loads for example service loads, loads from ships, and loads generated by the impact of sea waves.
Despite that fact that the life span of majority of marine structure is around 25 years but there are structures which have been in service for about 75 years and even over 100 years occasionally.
Marine structures are mostly divided based on function and they will be explained in the following sections.
Fig.1: Marine StructuresTypes of Marine Structures and their Uses Following are the different types of marine structures:
- Berthing facilities
- Dry docking facilities
- Coastal protection structures
Berthing Facilities in Marine StructuresThese types of structures are used for many purposes for instance to provide supports for ships and to facilitate good and passenger movements between ships and land transportation. These facilities may be constructed normal to the shore and parallel to the shore based on the application of the structure. Types of berthing facilities involve piers and wharves.
Piers in Marine StructuresPiers are built normal to the shore and extended from land along the edge of sea into the deep water and either side of piers can be applied for berthing. The length of the pier is determined based on the length of the largest ship that may utilize it, so the length of the pier is either equal or longer than the ship length. Not only does the structural considerations are considered while the width of the pier is specified but also both geotechnical and functional considerations as well. There are three kinds of piers including open pier, closed pier, and floating pier. As far as open piers are concerned, they are either single or double deck structures which are sit on piles and permit the flow of water under the structure.
Fig.2: Pier Structure
Fig.3: Single Deck Pier Structure
Fig.4: Double Deck Pier StructureSolid fill or closed piers consists of a structure such as quay wall, anchored sheet pile, or bulkhead which support earth fill behind it, provides working area. It does not allow discharge of water under the structure. There is a specific type of solid fill pier called mole pier which is built and extended from land on the edge of the sea into water. Concrete sheet pile or masonry is employed on either side of the structure to support the material behind it.
Fig.5: Solid Pier StructureFloating piers are either single or double deck structure which is joined with to land through access ramp. Either chain anchorage system or other appropriate means are employed to avoid structural movement laterally and facilitate movements vertically during water wave fluctuations. Figure-7 shows different types of floating pier structure.
Fig.6: Floating Pier Structure
Fig.7: Floating Pier Structure Details
Wharves in Marine StructuresThese platforms are built nearly parallel to the land on the edge of sea and most wharves are not connected completely to the shore. Bulkhead or quay walls are used to support fill materials or stones behind the structure. Unlike pier, ships can be supported only at one side of the wharf. Structural, geotechnical, and functional considerations are considered when the width of the wharf is specified and wharf length depend on the length of ships which may use the structure. Solid fill (Figure-11) and open (Figure-9 and Figure-10) platforms are the major types of wharves. Wharf structures supported by piles may be built at specific distance away from the land on the edge of sea if the water close to land is not adequately deep and ships with long draft cannot get close to the structure without damages. This structure is connected to shore by trestles (Figure-12) fixed on piles.
Fig.8: Wharf Structure
Fig.9: High Level Fixed Wharf
Fig.10: Relieving Wharf Structure Type
Figure 11: Solid Fill Wharf
Fig.12: Trestle Structure
Dry Docking Facilities in Marine StructuresThese types of structures are utilized for building ships and to inspect, maintain, repair, and modify ships. Types of dry-docking platforms are floating dry dock, graving dry dock, vertical synchro lifts, and marine railways.
Floating Dry Dock in Marine StructuresThis type of structure is built like U letter and is employed to lift ships out from water by filling the platform with water, then the ship will be moved inside the dock after that the water will be drained out from the dock.
Fig.13: Floating Dry Dock
Graving Dry Dock in Marine StructuresIt is a container built from concrete, masonry, sheet pile, or stones adjacent to the land on the edge of sea. When a ship enters the structure, the platform is closed by water impervious barrier. After that, the water will be pumped out water from the structure and permit the ship to settle on blocks fixed inside the structure. Figure-14 shows typical graving dry dock structure.
Fig.14: Graving Dry Dock
Fig.15: Graving Dry Dock
Vertical synchro liftsVertical synchro lifts as shown in Figure-16 is composed of structure that is moved down into the water then the ship will be loaded and rise to determined location.
Fig.16: Vertical Synchro Lifts
Marine RailwaysMarine railways facilitate the movement of ships or containers into the water and out of water. It consists of ramps that reach to water body, hosting equipment, a mobile ship cradle on rollers, ground-way ship cradle tracks, and cables for hauling ship cradle. Figure-18 illustrates various parts of railway platform.
Fig.17: Marine Railway
Fig.19: Marine Railway Parts and Details
Coastal Protection StructuresThe major motivation to build this type of structure is create a barrier between sea waves and structures such as harbors in order to avoid detrimental effect of sea waves like erosion. There are various types and arrangements or configuration of coastal protection structures includes bulkhead (Figure-20), seawalls (Figure-21), groins (Figure-22), jetties (Figure-23), and breakwater (Figure-24). Read More: Types of Coastal Protection Structures and their Details
Fig.20: Bulk Heads View from Side
Fig.22: Groin Structure
Fig.23: Jetty structure