Technical specifications

Scope of works:

Mine water drainage tunnel

  • Length: approx. 7,400 m
  • 2 drives: West 3,230 m and East 3,8700 m in length
  • Internal diameter: 3.60 m
  • External diameter: 4,50 m
  • bore diameter approx. 4.80 m
  • 230 m open cut tunnel section with retaining wall comprising bored piles And a 30 m long launching box for the TBM boring the west section up to a central shaft.
  • Central shaft approx.. 75 m deep, internal diameter approx. 75 m deep, internal diameter approx.. 32 m.

Construction method:

  • Parallel excavation of the tunnels from 2 access points using 2 Variable-Density-TBM’s (VDS), diameter: 4.80 m, Tunnel lining using reinforced concrete segments,

    Construction of the west launching box using secant pilling and central shaft using anchors and sprayed concrete


  • Sand, gravel, sand-/lime-/mudstone, coal seams and adits

General data

Mine Water Drainage Tunnel, Ibbenbüren, Germany

RAG Aktiengesellschaft, Ibbenbüren, Germany

Wayss & Freytag Ingenieurbau AG in Joint Venture

Construction period
November 2021 to May 2025

Mine water drainage tunnel
Approx. 7,400 m
Construction Method
TBM tunnelling using two VD TBMs

More Information:

The central shaft will be used as the reception shaft for the west section TBM and as the launching shaft for the TBM boring the east section up to the existing shaft “Schacht 1 Oeynhausen”. After TBM reception, this 100 m deep shaft will be strengthened. The drainage tunnel will drain the mine through the segment lining into an invert precast channel, which transports the drained water towards the west, out of the mine into the sewage treatment plant Gravenhorst. The two drives will be bored partly with pea gravel sections, where mine water drainage is required, and partly with 2K-grout sections as segment lining backfill, where mine water drainage is not required.

A particular challenge arose due to the location of the construction site in an inner-city park, which meant that only a tightly dimensioned installation area was available. Considerable restrictions also had to be taken into account in the delivery of the jacking pipes with an outside diameter of 4,500 mm and an individual weight of approx. 32 tons.

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