Smart combo wall shares real-time information

Because container volumes in the port of Rotterdam are expected to continue to grow strongly in the coming years, the quay in Princess Amaliahaven is being extended. The construction of new deep-sea and inland waterway quays allows transhipment companies to further develop the still derelict sites around this part of the port. In order to monitor the behavior of the quay structure both during the installation phase and during the operation phase, the Port of Rotterdam Authority is using a 'smart' combi wall supplied by ArcelorMittal Projects.

ArcelorMittal is a well-known name in the port area. "In the past, in cooperation with the Port of Rotterdam Authority, we assessed the mother tender for feasibility, in which we included our years of experience. This sets out the quality requirements that the steel for the combi walls must meet," begins Patrick Mulders of ArcelorMittal. "So we are familiar with all the requirements and have prepared standard quality documents such as ITPs (Inspection and Test Plan), a quality plan and measurement reports. There are additional requirements such as the straightness of the tubes and an additional testing regime that allows deployment of stock tubes. Random sampling is used to verify with lock teller systems that the sheet piles have indeed remained in the lock."

The new deepwater and inland quays are designed as a combi wall: pipes with ditches and intermediate boards. "Considering the length of 2.4 kilometers of new quay wall, these are huge quantities," Mulders said. ArcelorMittal is supplying 15,000 tons of pipe material and 5,000 tons of sheet piles. "As ArcelorMittal Projects, we were able to confirm to the very challenging schedule of the project through a combination of our stock pipes and newly produced pipes. All the steel was transported from the production sites by ship to a purpose-built unloading quay in the Princess Amalia Harbour."

Apart from its size, this project has another special feature. In fact, about five tubular piles were equipped with a monitoring system. "The system consists of a fiber optic cable glued on both sides along the entire length of the tube pile. There is also a reference cable for temperature measurements," Mulders explains. "Over this, a steel protective sleeve is placed so that the system cannot be damaged during transport and installation at the construction site. With this system, the port authority is able to monitor the strain in the pipe pile while filtering out temperature influences. It provides insight into how heavily the pile is loaded and whether deformation occurs. On the one hand, you can use it to test the design model and, on the other, the condition of the structure over time. More load on the structure (physically observable or due to corrosion) is reflected in the fiberglass results."

The monitoring system was extensively tested on the ArcelorMittal site. Mulders: "All five tubular piles were tested for operation and compared with the predictions. First, baseline measurements were performed by placing the tube piles on H-beams for a load-free bearing. Then they were further tested by building up the load on the tube by means of an auger in several steps. That way we were able to measure the deflection and the load in the tube." As a backup system, the five tube piles are equipped with two additional protective sleeves. Should anything go wrong during installation, new fiber optic cables can be installed afterwards through grout injection. Meanwhile, the entire combi wall has been successfully installed, including the five tube piles with the monitoring system distributed over the 2.4-kilometer quay. 

The concept of the smart combi wall in the Princess Amaliahaven fits seamlessly with ArcelorMittal's recently introduced SmartSheetPile concept. "Depending on the demand from the client, we can provide a project-specific interpretation of the concept," says Mulders. "Using sensors, all kinds of parameters are imaged, both during installation and during the operating phase of the sheet piling. Think, for example, of measuring strain and deformations, but also monitoring corrosion during the service life. It is also possible to observe impact loads and misalignment. Data are monitored in real time and sent to an online dashboard. The goal is to get an even better grip on the behavior and performance of steel structures. It can lead to the development of new models, new calculation methodologies and ultimately to optimizations of steel usage."