SAFETY FIRST IN FROZEN BORE

Nitrogen ground freezing has become necessary to overcome very confused ground conditions over some 55 m of the 6 km long, 2.44 m internal diameter concrete lined tube needed to provide an alternative water supply for London should the River Thames become polluted. At the site, running sands and silt are under considerable artesian pressure. Claquage grouting was tried but was needed to be supplemented by ground freezing. Nitrogen freezing was chosen in preference to brine because it stiffens the ground within 48 hours. Health precautions, which are vigorously enforced, are divided into two types, above and below ground. There is little danger of nitrogen asphyxiation above the ground, but cold burns provide a more serious threat, and the use of leather gloves is compulsory. Maintenance of freeze around the shield is carried out during the shift changeover period and no general freezing is carried out within 4 m of the face when working. Only one man is allowed in the tunnel to measure oxygen deficiency at a start of a shift. Good communications between the face and the freezing operation are essential to ensure nitrogen is not fed to a pipe which has been cut at the face. (TRRL)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/03077683
• Corporate Authors:

  Institution of Civil Engineers

  One Great George Street, Westminster
  London,   United Kingdom  SW1P 3AA
• Authors:
  • Dadson, J
• Publication Date: 1984-10

Media Info

• Features: Figures; Photos;
• Pagination: p. 26
• Serial:
  • NEW CIVIL ENGINEER
  • Issue Number: 612
  • Publisher: EMAP CONSTRUCT LIMITED
  • ISSN: 0307-7683

Subject/Index Terms

• TRT Terms: Asphyxia; Freezing; Ground freezing; Injuries; Nitrogen; Personnel; Pipe; Pipelines; Prevention; Safety; Sand; Silts; Water
• Geographic Terms: United Kingdom
• ITRD Terms: 3601: Freezing (method); 2163: Injury; 7128: Nitrogen; 102: Personnel; 3361: Pipe; 1665: Safety; 4105: Sand; 4149: Silt; 8119: United Kingdom; 4355: Water
• Subject Areas: Construction; Geotechnology; Highways; Pipelines; Safety and Human Factors; Security and Emergencies; Society; Terminals and Facilities; I51: Earthworks and Soil Drainage;

Filing Info

• Accession Number: 00394570
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD, TRIS
• Created Date: Jul 31 1985 12:00AM