New Mainz Tunnel
In connection with the renewing of the existing rai l link between Mainz and Mannheim, the new Mainz tunnel is built as a two-track tunnel in the city of Mainz between the main railway station and the southern railway station. The new tunnel is situated very near to the old, still existing tunnels of Mainz. The depth of the mountain covering is 4 to 22 metres. The new Mainz tunnel is driven in the tertiary layers of the Mainz basin. The levels are composed of marly clays, marly limestones, sandy silts as well as individual limestone banks. The clays to be dealt with consist of inclusions containing fine sand, coarse silt and silty ribbons. The limestone ribbons reach from a compact and massive to a decomposed condition. Above the tertiary layers, a height of about 11 m has been filled up since the Roman Settlement due to their multiple construction actions. There is sectional ground water existing up to rail level. On long distances, the tunnel under drives existing roads, buildings and medieval fortifications. Owing to this fact, an especially resistant construction will be necessary. Tunnel excavation is done in four partial sections (two sidewall galleries, crown and invert secton). The quick closure of the annulare section in all partial sections as soon as possible, heading pipe roofing under existing buildings, injections into the ground and from the side of the tunnel, the limitation of distance between sidewall galleries and crown excavation and an early placing of the internal leaf (120 metres behind the front) contribute to a construction of minimised settlement. The excavation in all sections is done by means of tunnel excavator. The excavated ground is fixed by steel fabric mats, tunnel arches, shotcrete and rock bolts. The inner leaf is constructed in water-resistant concrete in lengths of 8.80 metres and in two parts as invert and crown section. Approximately in the middle of the tunnel length, a rescue tunnel is driven from the main tunnel to the existing cut between the two old Mainz tunnels. The tunnel construction works are connected with extensive measurements and evidence securing programmes at the respective constructions, on the surface and within the tunnel. Thereby elektrooptical deformators, levels, extensometers and inclinometers, measurement bolts and pressure cells are inserted. The extensive measurements are electronically evaluated and permanently mailed in diagrams or tables to the involved tunnel experts. The tunnel is driven from the northern portal, very near to the existing railway tracks. Owing to the unfavourable street connections, the haulage of the tunnel debris and the supply with construction materials for the whole drive is arranged via rail.
- Country: Germany
- Region: Rheinland-Pfalz
- Tunnel utilization: Traffic
- Type of utilization: Main-line rail
- Client: Deutsche Bahn AG
- Consulting Engineer: Krebs und Kiefer
- Contractor: C. Baresel AG, Porr, Asdag Tunnelbau GmbH, Allbau GmbH
- Main construction method: Trenchless
- Type of excavation: Excavator
- No. of tubes: 1
- Tunnel total length: approx 1.304 m
- Diameter: 11.90 m
- Cross-section: 139 m²
- Contract Volume: DM 86,000,000
- Construction start/end: 1997 till 2000
- Opening: by the middle of 2001