Introduction
Floating docks and protective barriers cost often less to build than traditional fixed structures. They do not rely on heavy construction works, which can be costly and time consuming. Installing a prefabricated floating structure is generally much less disruptive to the berth’s immediate surroundings.
As the mining industry spreads into ever more remote settings, port construction must keep pace. In many of these locations there is limited access by road, rail or air, leaving water as the remaining route. A wise engineer will turn this to best advantage by designing a structure for the simplest possible delivery and installation, using the minimum of land-based heavy equipment. Floating structures have a long pedigree in urban settings. Recent innovations in floating protective barriers may extend their applications even further. This article will look at one installation in the fast developing mining industry of West Africa, and another in the heart of London.
Despite their superficial differences, the projects draw on a common design approach. They both incorporate fender systems into a much larger, more complex whole. Simply choosing components from a fender catalogue will no longer do. Stepping beyond traditional fendering and structures has many attractions, but there is no free lunch. New design methods and technologies are called for, and they must be properly integrated into every step of the design process.
QuayQuip has invested substantially in the latest generation of solid modelling, finite element (FE) analysis, soil analysis, and three-dimensional visualisation software. In doing so, it created a new design team with real world experience of these tools in civil and mechanical engineering applications, and in naval architecture. Solid modelling and FE tools allow designers to optimize structural designs and production requirements from the outset. Load ‘hotspots’ can be spotted promptly and eliminated. Visualisation tools afford non-technical decision-makers a clear understanding of the proposed design long before it takes shape in the factory. After approval, solid modelled designs can be quickly converted to production drawings to meet tight deadlines.
A floating dock at Marampa, Sierra Leone
Late in 2010, London Mining commissioned QuayQuip to design, manufacture, deliver and install a transhipment berth for their iron ore mining operation at Marampa, in Sierra Leone. London Mining’s Marampa Iron Ore Mine exports its output via a barge loading facility, 20 kilometers from the capital Freeport. Marampa lies on the northern bank of the Sierra Leone River’s vast natural harbor.
The tidal, floating, pile-guided berth is 260 meters long and comprises 22 modules, each 12 meters long and 3.5 meters wide. A 30 meter, fully articulated gangway was also supplied by QuayQuip, allowing operators easy access from the shore. On the riverbank behind the structure is a slewing ore loader. Built into the berth is a winch-controlled warping system. From a shelter mounted on the floating structure, a single operator controls the warping of barges along the structure’s face. Designers decided early on that a modular, floating dock would be containerized for delivery to Sierra Leone. Road and rail links between Marampa and the capital are still in need of development, so modules would be unloaded from containers for transfer along the river by tugs, which could deliver each unit precisely where it was needed.
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