Impact of fire on the stability of hard rock tunnels in Sweden

Safety in tunnels and mine drifts must have top priority so that people can travel and reside underground without being affected by accidents. Unfortunately, several tunnel fires around the world last 15 years have struck people, why safety should be prioritized everywhere. There is a need to know, not only how to build safe escape routes, alarm systems, videosurveillance etcetera, but also to have knowledge of the thermal properties for material in the tunnel systems. Rock is one of the main components in the structural system for underground hard rock openings. Often, the rock surface is covered with shotcrete, but thinner shotcrete protects the rock only for a short time. Thick concrete may spall successively. Rock subjected to high temperature, e.g. during a vigorous fire, will initially start spalling. The understanding of rock behavior during thermal spalling is limited, and the objective for research is to build knowledge. The research was, except for an initial literature survey, performed using rock samples heated in the laboratory to certain levels with a maximum of 1100°C. Three different rock types where used; granite, gabbro and schist. For different temperature levels the difference in material compressive strength, mineralogy, and micro-cracks where registered. By monitoring acoustic emission (AE) events at heating/cooling in 3D, the special micro-seismic even map was compared with other changes due to thermal change. Also, grain-scale numerical modelling and larger scale modelling (macro-mechanical model) were carried out as part of the project. A combination of several methods, as in this research project, will give more solid conclusions.


  • English

Media Info

  • Pagination: 130
  • Serial:
    • BeFo rapport
    • Issue Number: 136
    • Publisher: Stiftelsen Bergteknisk Forskning (BeFo), Sweden
    • ISSN: 1104-1773

Subject/Index Terms

Filing Info

  • Accession Number: 01664443
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • Files: ITRD, VTI
  • Created Date: Mar 28 2018 10:24AM