Ground movement studies carried out during the tunnelling trials in lower chalk at Chinnor, Oxfordshire, included measurements of the influence of tunnel excavation on an adjacent shaft. Vertical movement of the shaft wall was measured using a multiwire borehole extensometer mounted on the shaft parapet. The wires from the extensometer were attached to rockbolts in the shaft wall and final movements of up to 8.5 mm were recorded. Horizontal movement was measured by sighting targets attached to rockbolts in the shaft using a precise optical plummet mounted on the shaft parapet. Total movements of up to 7.5 mm towards the tunnel were recorded 2 M above tunnel axis level. One half of the shaft wall was reinforced by resin anchored rockbolts and the other half by mechanically anchored rockbolts. The section reinforced by resin anchored bolts showed somewhat less vertical subsidence than the wall reinforced by mechanically anchored bolts. In both cases, the amount of horizontal movement was similar. In this situation, with relatively poor quality chalk reinforced by rockbolts, the shaft was stable as the tunnel was driven past, only 1.75 M away at the closest point. (A) /TRRL/

  • Corporate Authors:

    Transport and Road Research Laboratory (TRRL)

    Wokingham, Berkshire  United Kingdom 
  • Authors:
    • HUDSON, J A
    • McCaul, C
  • Publication Date: 1975


  • English

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 21 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00132322
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Suppl Rpt.161 UC R&D Rpt.
  • Files: ITRD, TRIS
  • Created Date: Jun 23 1976 12:00AM