A9: Smart solution for testing anchor piles near sheet piling

On behalf of Rijkswaterstaat, VeenIX is widening and deepening the A9 between Badhoevedorp and Holendrecht. Near Amstelveen, the A9 will be deepened over a length of 1.6 kilometers. The location of the future deepening has been divided into 18 construction pits by placing sheet pile walls. Construction combination VeenIX engaged High5 Solutions to install approximately 2,000 self drilling anchor piles type C. These will hold the underwater concrete in place and later serve as foundation piles of the sunken basin. For this, High5 Solutions devised a special lever construction from a pontoon for testing the piles. 

"We work faster and cleaner thanks to sonic technology. That means less energy and less grout needed," says Timo Gijbels, head of H5S' business office and also involved as a work planner on the A9 Badhoevedorp-Holendrecht. "Our drill motor not only rotates, but also vibrates with a special sonic vibration. That vibration is very fast, between 150 and 180 times per second. These sonic vibrations allow us to drill more easily through very hard sand layers and consume less grout. In addition, the high frequencies of the vibrations have hardly any effect on the environment." High 5 Solutions, also known as H5S, is a young company focused on foundation engineering. They use a unique drilling and vibration technology that they invented and patented themselves. With this they make grout anchors and anchor piles, among other things. They also apply other grouting techniques, for example to prevent subsidence of buildings or pipes. "The sonic technique is also well suited to other drilling and vibration work in construction, infrastructure, offshore and environmental projects. Think of destructive pre-drilling of obstacles, such as existing quays or pile foundations. We work in the Netherlands, but also abroad. Projects we are proud of include the Maas Delta Tunnel, the dike reinforcement between Tiel and Waardenburg, and the Ocean Reef Island project in Panama."

Special lever construction

At the A9, H5S is installing about 2,000 self-drilling Type C anchor piles along the edges of the construction pits. In addition to placing them, H5S is testing whether the piles are secure; they are doing this together with an independent company. What is special about this project is that the tests have to be done from the water. "If the piles are in the middle of the construction pit, we can easily test them from a pontoon. But we just placed the piles along the edge, close to the sheet piling. Then the standard method doesn't work." H5S came up with a clever solution: a special lever construction. Here, the test beam lies both on the pontoon and on the sheet piling. This construction has not been used before in the Netherlands for this type of testing. "We push the pontoon down into the water with a jack construction. Because the pile is at a distance, a lever is created. In this way, we were still able to pull 150 tons on the pile with a small pontoon and relatively little force." H5S also conducted failure tests on their Type C anchor piles prior to installation, "demonstrating that the production piles meet the optimized factors of the design."

Working under limited height

At VeenIX's request, H5S also installed anchor piles under the two temporary auxiliary bridges. "Under these auxiliary bridges we had to deal with a limited height. For this we adapted our drill by shortening the broker. That made us the only party that could install the anchor piles under these auxiliary bridges." 

Proud

The A9 is a multi-year project that demands a lot from a relatively small company like H5S. "There are also quite a few complex issues in it, such as the weight of the piles and the sunken installation of up to 10 meters below ground level. This, together with the failure tests and suitability tests, means that you are working at a high level of quality. That makes us extra proud to be able to contribute to this piece of infrastructure in the Netherlands."