Innovative Use of Fabric-Formed Concrete Mattresses for Scour Protection Under Pile-Supported Berths: Case Study from Specialized container facility Manzanillo Port, Mexico

Abstract

The expansion of the specialized container terminal in the Port of Manzanillo (Mexico) required a robust scour protection system under a new dock supported by piles, subjected to severe hydraulic loads generated by the propulsion system of the vessels including ships of the Megamax 24 class. The original design envisaged a 1.2 m (3.94 ft) thick rockfill layer over 13,500 m² (145,300 ft²) (geometric area), exceeding 16,200 m³ (21,190 yd³) equivalent to more than 29,000 tons of rock , to be placed after the installation of the piles and at the same time of the construction of the structural slab for the dock – placing the scour protection construction process in the critical path of the project. Logistical constraints, construction risks, reduced maneuvering space under the dock, and considerable environmental footprint led the contractor to evaluate alternative systems. An international team composed of specialists in port engineering, geosynthetics, and the manufacturer of the solution, selected an articulated Fabric-Formed Concrete Mattress, 30 cm thick (12” in), reinforced inside with a 30 mm circunference high-strength polyester cables, after a hydraulic evaluation based on PIANC. The system reduced material demand from ~13500 m³ of rock to ~4500 m³ of locally produced concrete, allowing for continuous coverage around the piles, better adaptation to seafloor irregularities, and greater hydraulic stability against propulsion systems of the vessels. Custom panels were designed, capable of being installed underwater, with controlled geometry, internal stabilization cables and permeable joints to relieve hydrostatic pressures. The underwater formwork installation hit a production rate of about 1,180 m² per week, and grouting averaged roughly 1,050 m² per week. These numbers are on the conservative side, since port operations started right away and the constant arrival of vessels limited our ability to grout continuously with controlled injection down to –18 m (59.1 ft). The solution accelerated construction schedule, reduced the carbon footprint, eliminated the formation of gaps typical of rockfill in confined geometries, and ensured long-term scour protection performance. This case demonstrates the technical, economic, and environmental advantages of articulated Fabric-Formed Concrete for confined marine environments.