Tunnel Hainrode-Nord
The Hainrode Tunnel was certainly one of the trickiest projects on the new line between Hanover and Würzburg. The tunnel with a total length of 5.3 km was driven in two lots. The lot "HTN" was roughly 2,800 m long with tunnel cross-sections between 120-140 m². The geology mainly comprised variegated sandstone (layers of sand with clay intercalations). The tunnel was lined with a 30-40 cm thick, reinforced in-situ concrete shell. In order to cut down on construction time, an access tunnel was built providing three points of attack for driving. In retrospect, this decision was well worthwhile as considerable geological problems were encountered in the section north of the access tunnel. Ordinary securing measures (reinforced shotcrete, support arches, bolts and lances) did not suffice in this section. Grouting, wells for lowering the groundwater and crown bases were needed. It even turned out to be necessary to drive a fore gallery some 100 m in length. Thanks to the access tunnel, there were no delays in spite of these difficulties, which had unexpectedly cropped up. The main drive towards the south progressed unhampered. In the so-called "Hainrode Fault ", an area known for its pronounced geological disturbances, the groundwater was lowered from the ground surface with wells more than 100 m in depth. To strengthen the extremely disturbed rock in the fault zone, a stronger lining was chosen comprising reinforced support arches, stiffened, two-layer shotcrete reinforcement, 40 cm shotcrete thicknesses, bolting system with 8 m long self-boring grounding anchors. Thanks to these measures, it was possible to complete the tunnelling of the "Hainrode Fault" section on schedule without any unusual incidents. In this section, the inner shell was 60 cm thick.
- Country: Germany
- Region: Hessen
- Tunnel utilization: Traffic
- Type of utilization: Main-line rail
- Client: Deutsche Bahn AG
- Main construction method: Trenchless
- Type of excavation: Drill & blast
- Lining: Concrete formwork (reinforced)
- No. of tubes: 1
- Tunnel total length: 5370 m
- Cross-section: 120 to 140 m²
- Contract Volume: approx. 218 mill. DM
- Construction start/end: 1981-1987 (55 months)
- Opening: 1987