Construction of a 405m long jetty, 16m above sea level
As part of the Moma Heavy Mineral Sands development in Mozambique, Dura Soletanche Bachy was awarded Group Five the contract for works involving maritime piling and the construction of a jetty stretching 405m out to sea at an approximate height of 16m above sea level.
The alternative solution selected involved the installation of 95 no piles 610mm diameter metal piles for the jetty and 1,200mm diameter piles for the berth and moorings. The jetty were put in place from the banks using the “leap frogging” progress method: the piling rig moves forward as the piles are installed.
The steel pontoon sections were assembled on the site, the tubes were transported from Johannesburg to Moma in 12 m sections and then the pile tubes butted welded together to produce 36m long tubes.
Construction works commenced on the bank with the assembly of the RB61 crane and the main carriage “Boggie” specially designed and constructed by Dura Soletanche Bachy to run on rails along the jetty for the purpose of transporting the crane, the pile centering frame that allowed the piles to be installed as per specifications, the PTC50 vibratory driver and its power pack.
The 36 m long piles were collected from the welding area by an RB38 crane and transported the length of the jetty by two transport carriages up to the main carriage of the positioning crane. The piles were then vibration driven to set in one single length down to their final depth under the action of a 6 tonne hammer. Once the piles had been driven in pairs (“bent”) a bolted steel section of pontoon was added to act as a walkway. Every 48 hours, the carriage and the crane advanced by 9m to the next “bent” Nº 46 (92 piles), or a distance of 405m where finally drenched.
The 3 no 610mm diameter piles were constructed along the jetty for a loading area, together with six 1,200mm diameter piles, excavated and concreted for berthing and mooring.
Dura is proud to disclaim that no accidents were registered since the beginning of 2013 thus all the effort being put into safety procedures and training is allowing us to achieve our ZERO Accident Objective. ...
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