AVND-machines: when things become more difficult.
AVND-machines are an expansion of AVN-technology for added safety in difficult geological conditions and large diameters. The support pressure is controlled via an adjustable compressed air cushion.
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data sheet AVND 1600 AB- AVND 2200 AB
data sheet AVND 2300 AH - AVND 4000 AH
data sheet AVND 2400 AB - AVND 3000 AB
Portland Westside CSO Tunnel, USA
As part of the "Combined Sewer Overflow (CSO)" project, Portland is building a sewage pipeline which feeds into the West Side Tunnel. For this job, the Microtunnelling machine must be particularly flexible because it needs to excavate at varying diameter. A AVND1800AB Utility Tunnelling Machine is being used here. The maximum daily advance was a stunning 58m in 24 hours. At the same time, the machine is particularly flexible and can be upskinned quickly and easily.
Cable tunnel Seoul, South Korea
This demanding project is carried out using an upskinned AVND2400AH: 800m of excavation of a route with five tight curves (radius between 200 and 250m). Despite the extreme abrasiveness of the granite rock the thrust can be kept lower than expected thanks to the automatic lubrication system. Ultimately, only 4 out of 9 intermediate jacking stations have to be employed. Due to the tightness of the jobsite at the launching shaft, the pipes have to be delivered just-in-time. Another challenge lay in the safe excavation to the cellar of the multistory building housing the subway station. In the densely developed Seo Cho area excavating a deep target shaft would have meant having to block off one of the busy roads completely, which was not an option. The "mother of Pipe Jacking" was successfully completed in March 2003.
Newa Crossing, St. Petersburg, Russia
The construction of a tunnel for an oil pipeline in St. Petersburg faces complicated geological conditions consisting of extremely fine sand mixed with clay. As an additional difficulty, the tunnel must be built underneath the bed of the river Newa, which is an important source of drinking water for the city and an important waterway which cannot be blocked. The tunnel was excavated up to 20m underneath ground water level, sometimes only 7m underneath the river bed. To meet project requirements, a Herrenknecht AVND2000AB Hydro Shield was used to excavate the 775m tunnel under high ground water pressure. A compressed air cushion in the excavation chamber controls the tunnel face support, ensuring safe excavation even under varying geological conditions. Led by the LNS-P laser guidance system, the machine managed a daily advance average of 21m, along a 7-degree gradient and with high accuracy.
