The joint venture of Tunnel Ibbenbüren, comprising Wayss & Freytag Ingenieurbau AG and ZÜBLIN, has successfully completed the final tunnel breakthrough on the Grubenwasserkanal Ibbenbüren project in North Rhine-Westphalia, Germany.
The project involves the construction of a 7.1km mine water drainage channel, aimed at sustainably managing water from disused coal mines.
The final breakthrough marks the completion of a 3.8km section of the tunnel.
Two Herrenknecht Multi Mode tunnel boring machines (TBMs) were used on the project.
These machines can switch between different tunnelling modes quickly and without mechanical conversion, allowing them to adapt efficiently to changing geological and hydrogeological conditions along the alignment.
This was essential given the variability of the terrain, which ranged from stable rock to soft, waterlogged material.
With a diameter of just 4.74m, the TBMs had to be both compact and versatile.
The design allowed for flexible backfilling of the annular gap with either mortar or pearl gravel, depending on the tunnel segment.
Approximately 60 percent of the route required backfilling with pearl gravel to ensure proper drainage of mine water into the tunnel.
The project also required close interdisciplinary collaboration, with engineers across multiple disciplines of electrical, hydraulic, and mechanical working together to create a tailor-made tunnelling system.
Additionally, the confined underground environment presented challenges for the navigation systems used, which were developed by VMT GmbH.
The successful completion of this tunnel section represents a significant step forward in efforts to sustainably manage legacy mine infrastructure.
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