Construction of three vertical shafts using upward shield machine - the Bandai-Hannan sewer tunnel construction works

The Bandai-Hannan Sewer Tunnel which is about 2 km long and has a finished inner diameter of 3.25 m was constructed in the southern part of Osaka City, Japan to mitigate a flooding problem in the area. A total number of seven vertical shafts were installed within the tunnel route. These vertical shafts are for the purpose of draining water from existing sewer mains, ventilation and inspection purposes. Three of the said vertical shafts (finished diameter 2 m; with depths ranging from 13.5 to 25.9 m) are located adjacent to a narrow and heavily trafficked road within an area of low-rise timber houses. The traditional method of constructing vertical shafts is from ground level downwards which disrupts traffic flow and affects the daily activities of local residents. An ''Upward Shield Construction Method'', which excavates upwards from the tunnel, was adopted. An Earth Pressure Balance shield machine was specially designed and manufactured for construction of the three vertical shafts. The dome shape cutter was equipped with four cylindrical spokes and blades for mixing spoil were installed inside the cutter chamber. A funnel shape chamber was designed to increase the efficiency of channelling excavated spoil to the central spoil discharge pipe, hence minimising the accumulation of residual spoil inside the chamber. Two pinch valves were installed in the spoil discharge pipe to stabilise the earth pressure at the cutting face and to control spoil quantity. In order to simplify and expedite the shaft excavation operations, special concrete segments reinforced with carbon fibre reinforced polymer (CFRP) were installed in the sewer tunnel at the launching point of the vertical shaft. These special segments could be cut through directly by the shield machine. In general, a stable state of excavation was achieved for the vertical shaft irrespective of excavation speed and geological layers, except at the launching and arrival points. It was also demonstrated that the method could be used at a depth of 50 m below ground during a trial investigation. Settlement and displacement of the surrounding ground and sewer tunnel was also monitored. The settlement and displacement was found to be negligible and caused no surface settlement problems. Steel segments (8 segments/ring) weighing about 40 kg each were erected manually to support vertical shafts. In conclusion, the Upward Shield Construction Method introduced in this project successfully shortened the construction period by one third and surface operations by one sixth compared with traditional construction methods. In addition, noise pollution and vibration resulting from work activities, as well as disruption to the traffic flow and daily activities of local residents were minimised. (A). "Reprinted with permission from Elsevier". For the covering abstract see ITRD E124500.

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  • Authors:
    • KONDO, F
    • SAKAMOTO, H
    • TAKAISHI, T
    • MUAKI, T
  • Publication Date: 2004-7

Language

  • English

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Filing Info

  • Accession Number: 01011642
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Dec 19 2005 3:22PM