References
Terminal Cuenca del Plata
URUGUAY, 2009
Constructing an extension to the Cuenca del Plata port terminal as a general contractor
Soletanche Bachy, in a JV with Saceem, was awarded the turnkey contract for the construction of the extension to the Cuenca del Plata container terminal at the port of Montevideo. The extension to the existing quay comprised a new Danish quay 350m long, 35m wide, with a draught of 14.5m, as well as an 85,000m2 container storage area.
Reinforcement of the existing quay
Initially, jet grouting columns were installed in order to reinforce the foundations of the existing quay, which was built almost 100 years ago. A curtain of sheet piles was also constructed at the end of the quay to avoid any risk of undermining during the dredging phases.
Storage area
The storage area was reclaimed from the sea using 1 million m3 of shell sand dredged from the River Plate and then improved by vibroflotation. In addition, 120,000 metres of drains were installed in order to complete consolidation of the clay bank along the length of the existing works as it could not be dredged.
Extension to the quay
The Danish quay principle, i.e. constructing concrete slabs on piles, was chosen for the extension to the quay due to its non-invasive geometry and its easy interface with the existing quay. The new quay features 4 lines of 60 driven metal piles measuring 1,000 and 1,100mm in diameter.
An adapted method
The construction method chosen enabled disruptions to the port operations to be minimised. All the construction phases were carried out from a mobile platform, laid out along the line of the quay’s piles. A special platform was designed that featured neither bolts nor fastenings; it was laid on the piles and could be moved in less than 3 hours.
Initially, the piles were driven in using a vibrating hammer and were then driven to refusal using a 10-tonne hydraulic hammer. Once the piles had been set to the correct level, the platform could be moved along the line. The quay’s framework generally consisted of prefabricated slabs and beams. The last stage involved the civil engineering teams, who cast the final quay prior to installing the various apparatuses and handing the quay over to the operator.
Techniques
Regardless of site size, and providing it involves a significant proportion of works in the ground, Soletanche Bachy will handle the complete project, and all aspects of the works, including site supervision, excavations, foundations, civil engineering and all construction operations.
Jet grouting is a construction process that uses a high-pressure jet of fluid (generally 20 – 40 MPa) to break up and loosen the soil at depth in a borehole and to mix it with a self-hardening grout to form columns, panels and other structures in the ground. The parameters for the jet-grouting process and the desired final strength of the treated soil depend on a number of characteristics, such as the soil type, the technique used and the objective to be reached. In granular soils, the high-pressure jet breaks up the grains through erosion, while in a cohesive soil, such as clay, the jet breaks the mass up into small particles. High pressure is needed to produce the kinetic energy required for the jet through a small-diameter nozzle. Waste material from the process (a mix of soil, water and binder) is recovered at the surface before being taken away for disposal.
A pile is a structural element driven into the soil for transferring loads and prevent deformation. Its slenderness ratio is not limited.
Pile shafts can be uniform and rectilinear, telescopic and belled out.
Piles can be installed either separately or in groups. They can also form a retaining wall, a mixed curtain wall, contiguous piles, secant piles and composite curtain walls, such as Berlin walls and similar. Piles are also used as precast beams to be placed in the structure of the building they support.
Soil-improvement techniques involve changing soil characteristics by a physical action, such as vibration, or by the inclusion or mixing in the soil of a stronger material. The aim of this process is as follows:
- increase the load-bearing capacity and/or the shear strength,
- reduce both absolute and differential settlements or in certain cases, accelerate them,
- to mitigate or remove the risk of liquefaction in the event of an earthquake or major vibrations.
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