Laboratory-scale intact and jointed rock masses were tested in field and laboratory experiments to investigate tunnel response in high stress environments. In most of the experiments the tunnels were modelled by a rigid-plastic foam polyurethane with a crush strength of 3.4 mpa (500 psi) and emphasis was placed on jointed rock parameters: joint sets (single set of parallel plane joints versus a double set of orthogonal parallel plane joints), joint plane angle with respect to the direct load direction, and joint spacing. Other parameters were loading stress, loading direction, and tunnel reinforcement strength. Results show quantitatively the increase in tunnel deformation in jointed compared with intact rocks, double versus single joint sets, and large versus small angle between the joint plane normal and the loading direction. A surprising result was the decreases in tunnel deformation with increases in the number of joints across a tunnel diameter. The efficacy of scale modelling with laboratory-constructed rock was tested by modelling complex reinforced concrete and steel tunnel reinforcements in jointed rock masses and comparing the results with large scale tunnels previously fielded in highly jointed granite. Tunnel response was reproduced in surprising detail, including concrete fracture, steel liner bending and fracture, and critical load to produce these responses. The scale models also allowed sectioning of the jointed rock masses to observe gross sliding along the joints that accompanied tunnel failure. For the covering abstract of the symposium see IRRD 284392. (Author/TRRL)

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 824-836

Subject/Index Terms

Filing Info

  • Accession Number: 00452606
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-89520-297-2
  • Files: ITRD, TRIS
  • Created Date: Aug 27 2004 9:59PM