Low-reflectivity quay for docking
In the construction of the Cala de’ Medici Marina, an original type of low-reflectivity quay for docking was used along the entire internal side of the outer breakwater.
The aims of the designers and implementing parties were as follows:
- designing a quay module with a high power of reducing wave action inside the port (reduced reflection coefficient) through the combined effect of the absorbing power of a low-reflectivity face and of the diffraction produced by the cell elements used to construct the quay. The cells were connected together obliquely by large “openings”. The system, combining and optimizing two concepts normally in use, has provided an effective and concrete power of absorption. In this case, the high residual wave action formed at the entrance is rapidly reduced a few metres long the quay;
- optimizing the sizes of the quay elements to contain construction costs and at the same time to be able to use better quality materials (use of Rck 45 N/mm2 concrete and AISI 316 stainless steel reinforcement);
- configuring the quay as an isostatic structure;
- producing reinforced concrete cells having geometry and sizes allowing easy prefabrication on shore or in a factory (guaranteeing better quality), and to transport, handling and install them easily (construction of modules for coupling with maximum weight 20-25 ton.);
- configuring and adapting the quay modules for placing them on the seabed at a depth of -2.5 to -5 m above sea mean level (depth adequate for the needs of a marina of any type and characteristics);
- obtaining a quay width not exceeding the minimum functional requirements (cost savings during construction) and at the same time providing a superstructure slab with a size adequate for the installation of cable conduits, while without having structures that are too thin and therefore technically “fragile”;
- reducing maintenance work on the structure to a minimum;
- maintaining a high quality standard of the work also in architectural and aesthetic terms.
The reinforced concrete modules for the Cala de’ Medici Marina were produced at a prefabrication factory (the construction site lacked sufficient space to do this since the entire work area was used for the construction of the artificial blocks forming the mound of the outer breakwater).
The works were entirely carried on shore using a excavator arm backhand employed to build the foundation base, and a 120 ton capacity crane used to position all the elements.
The preparation of the foundation base, the only critical operation of the entire positioning cycle, was conducted by a team of three specialized divers.
Once the modules were positioned, they were ballasted with rock forming a sloping wall, with slope 3/2.
Afterwards, the prefabricated slabs and the edge rib reinforced with AISI stainless steel were installed facing the sea.
This veil arranged projecting profile of the underlying septa prefabricated having a height greater than the thickness of the superstructure easily made up for the inevitable changes in percentage of the bench of imbasamento and mask any off-axis planimetric.
From the economic point of view, the construction of this quay has an overall cost of approximately 2,550 EUR/lm. The impact of the materials is 65%, with 20% for labour and 15% for construction equipment.