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February 2024

Challenging Ring Convergence Measurement

Due to the special drainage requirement of the Ibbenbühren Mine Dewatering Tunnel (OD 4.7m) in the North of Germany, pea gravel instead of the usual cementitious grout is used to fill the annulus gap between the ring structure and the natural ground.

However, as pea gravel blinding is not as defined as filling under pressure with cementitious grout, it is all the more important to control the clean bedding of the ring indirectly through the minimal or non-existent convergences.

In this case, our Ring Convergence Measurement System is the perfect solution. The sensors are very helpful, especially as in the small and very compact TBM there is rarely a line of sight between the individual points.
Why is this project with our customer Wayss & Freytag and Züblin so important for us at VMT?

  • Validation:
    Counting among one of the largest uses of our ring convergence measuring system RCMS so far, it demonstrates the performance of the system, even under severe tunnelling conditions.
  • Optimisation:
    Including 10 measuring cross-sections at a distance apart of 10 m and a span of at least 100 m, the project gave us the opportunity to optimise the sensor transmission rate.
  • Success:
    Providing an automated system that eliminates the need for separate evaluation and documentation of the measurements, we are happy to contribute to the overall success of the project!

Learn more about our automated Ring Convergence Measurement System.