Along the coast of Marken, Rijkswaterstaat is working on a sturdy, future-proof dike. We are placing various layers of sand against the existing dike. The soil here is soft and gradually sinks.
Without intervention, it would take years for the subsoil to become firm enough to support the weight of a new layer of sand. Therefore, the ground is drained with vertical drainage. For this, a striking machine is needed: the vibro system.
What is vertical drainage?
Vertical drainage consists of narrow strips of geotextile, a sturdy, water-permeable material, which are placed vertically in the soil. They effectively form highways for groundwater, allowing water to rise more easily and quickly. This accelerates the subsidence of the soil: a process that could take years without assistance but is significantly shortened thanks to the drains.
The role of the vibro system
The vibro system is a crane that drives these vertical drains deep into the soil. Sometimes up to 6 m deep. This creates a network of drainage channels in the soil, allowing the subsoil to stabilize more quickly.
36,000 strips
At Marken, the contractor is installing a total of approximately 36,000 of these drains, or strips of geotextile. A large part of these drains has already been installed. Installation occurs in a fixed pattern, with a drain every 1.5 m, both above and below water. The vibro system plays a key role in this. In areas where debris is present in the ground, a special variant of the machine comes into action: it vibrates the debris apart or aside, ensuring that the drains reach the correct depth.
Faster and smarter construction
Measuring equipment in the soil monitors the progress of the subsidence process. This way, the dike reinforcement team can adjust in time if necessary. Thanks to the vibro system, this process proceeds faster and with less risk of uneven settlement of the subsoil. The result: a dike that provides protection against the force of water for decades to come. And it all starts with... a vibration and strips of fabric.