TOP TEAM UTILISES BENTONITE FOR TUNNEL DRIVE

The article discusses the design of the hydroschild soft ground tunnelling machine and its use in the construction of the Wilhelmsburg sewer tunnel project. The machine is designed for sub-aqueous tunnelling in dense sand at a depth of 15-20 M although in this project the 4.34 M diameter tunnel had a minimum cover of 6 M beneath shipping channels. For this construction compressed air was used with a bentonite/water suspension as a soil sealing and stabilising fluid, which was also used to carry solid material to the surface. This was then separated and the slurry returned to the cutting shield for re-use. A feature of the machine is that the shield is introduced at an angle of 70 degrees to give protection against soil instability at the crown. The pressurised thixotropic fluid in front of the shield ensures continuous grout penetration into the surrounding sand leaving a continuous skin of bentonite gel on the tunnel surface. The finished tunnel lining was provided by pre-cast concrete segments bolted together in circumferential and longitudinal directions. /TRRL/

• Corporate Authors:

  Foundation Publications Limited

  7 Ongar Road
  Brentwood CM15 9AU, Essex,   England 
• Authors:
  • Braun, W M
• Publication Date: 1975

Media Info

• Features: Figures; Photos;
• Pagination: p. 40-44
• Serial:
  • Underground Services
  • Volume: 3
  • Issue Number: 2
  • Publisher: Foundation Publications Limited

Subject/Index Terms

• TRT Terms: Bentonite; Compressed air; Construction management; Cutting; Development; Equipment; Grout; Grouting; Precast concrete; Sand; Sewers; Shielding (Tunneling); Shields (Tunnels); Slurry; Soft soils; Soil stabilization; Tunnel lining; Tunneling; Tunneling machines; Tunnels; Underwater excavation
• Geographic Terms: Germany
• Old TRIS Terms: Shields (Tunneling); Slurries
• ITRD Terms: 4186: Bentonite; 3666: Construction method; 9013: Development; 3674: Equipment; 8125: Germany; 4729: Grout; 4792: Precast concrete; 4105: Sand; 3394: Shield driving; 3689: Soil stabilization; 3374: Tunnel; 3385: Tunnel lining
• Subject Areas: Bridges and other structures; Construction; Geotechnology; Highways; Vehicles and Equipment; I54: Construction of Tunnels;

Filing Info

• Accession Number: 00134387
• Record Type: Publication
• Source Agency: ARRB
• Files: ITRD, TRIS
• Created Date: Dec 15 1976 12:00AM