Distance-Heating tunnel HTL 1

In order to extend Berlin's distance heating network, the BEWAG commissioned the building of a distance- heating tunnel with an internal diameter of 4,100 mm and a total length of 3,600 m between the Reuter West heating power station and the Mierendorfplatz. The tunnel is capable of accommodating 3 hot water transport lines each with a diameter of 1,000 mm and a line of 600 mm diameter for cooling, ventilation and industrial water. The tunnel passes under roads, industrial terrain, the River Spree (twice), railway tracks and the Schloßpark Charlottenburg at a depth of roughly 20 m. At the beginning of 1986, the Ed. Züblin AG was commissioned to sink the shafts and build the tunnel. The job was carried out by thrusting in accordance with a special proposal using the combi-shield developed By Züblin. With the combi-shield, driving can be accomplished either under compressed air, with compressed air-membrane support or suspension-supported. The soil is excavated within the shield and transported hydraulically. The material was transferred to a separating plant located on the surface. The subsurface conditions that were encountered permitted driving to be executed under compressed air, in some special cases, when erratics had to be salvaged and given major permeability of the soil, membrane support was applied. Within the free part of the shield, even large boulders could be salvaged with relatively simple means. Compressed air of up to 2 bar was required owing to the depth of the tunnel. When roughly 80 % of the available jacking force was achieved, an intermediate thrusting station was installed. With a number of intermediate stations, it was possible to jack lengths of a km or more. The pipes were produced in a field factory some 3 km away from the construction site. The pipes were connected via a steel slip-on ring and a rubber seal and subsequent inner sealing of the gap between the pipe ends. 3,607 m of pipe line with an external diameter of 5,000 mm - corresponding to a concrete volume of some 30.000 m³ and roughly 70.000 m³ of soil excavation - had to be produced during a period of 12 months.

• Country: Germany
• Region: Berlin
• Tunnel utilization: Utilities
• Type of utilization: Supply tunnel for district heating
• Client: Berliner Kraft- u. Licht (BEWAG)-Aktiengesellschaft
• Main construction method: Trenchless
• Type of excavation: Pipe jacking
• Lining: Reinforced concrete pipe
• No. of tubes: 1
• Tunnel total length: 3607 m
• Cross-section: 5.00 m
• Contract Volume: 84 mill. DM
• Construction start/end: 1986-1987 (12 months)
• Opening: 1987