Monitoringmonumental Hunsingo lock 

Building next to a national monument is always challenging, especially when it is founded on a 'special' foundation. Reason enough for Strukton to pay extra attention to the Hunsingo lock dating from 1859 during the construction of the new pumping station, which is part of the New Water Works Zoutkamp project. Unihorn, part of Strukton, was called in for extensive monitoring work. 

"The Hunsingo lock is a monumental object, built with masonry on wooden piles with kesps and founded on the first sand layer," explained Remo Hofland of Unihorn. "Underneath that sand layer is a layer of old pot clay, which has the property of swelling when the top load is removed. This could lead to deformation and even rotation in all directions of the old lock. This could compromise the instability of the lock during the work. To prevent that, and to be able to take timely management measures in case of 'emergency,' monitoring during implementation is necessary."

Tachy and vibration meters

Unihorn has thus placed a tachymeter on top of the lock, on either side of the column walls, which measures itself 24/7 at fixed points in the environment. "That data is collected so that a possible deformation of the column walls can be detected early. The moment the limit is in danger of being reached, all alarm bells go off and construction is halted to take management measures. Fortunately, that was not the case here," says Remo, who explains that the tachometers have now been removed because construction has moved to the next phase and no longer has any influence on the possible deformation of the old lock. However, automatic vibration meters from Unihorn are still present on the project. "Furthermore, we still continue to manually monitor the lock periodically," he said.

Unihorn is an independent research, consulting and design firm and specializes in the niche of pavement investigations for roads, conditioning investigations and asset management. "We also make 3D designs for public spaces, roads and levees, do environmental research and have our own accredited laboratory for analyses. Finally, we are very active in the field of geodata and monitoring, such as here in Zoutkamp. In the Hunsingo lock, by the way, we also conducted crack width measurements at an earlier stage to monitor possible changes in existing cracks."