Deformation of small tunnels - IV. Behaviour during failure

  • Author(s) / Creator(s)
  • Tests on small circular openings have been conducted to investigate the deformation processes near tunnels at large depth or in weak rock. The test equipment has been described in Part 1; typical test results documenting the behaviour of small tunnels in a jointed rock mass with time-dependent strength and deformation properties have been presented in Part II; and the pre-failure behaviour of these tunnels has been investigated in Part III. In this fourth part, results from one specific test on coal are used to discuss the behaviour of openings in a jointed rock mass during the failure process. The test results show that it is necessary to differentiate between two modes of behaviour, yielding and rapture, if overstressing of the rock mass near the opening occurs. The observed rock mass displacements and wall convergences are compared with predictions made by one analytical and one numerical model. It is concluded that existing design models do not satisfactorily simulate the transition from yielding to rupture and that both behaviour modes must be evaluated separately for proper tunnel design and selection of optimal construction techniques. Practical implications for tunnel monitoring and interpretation of oil well breakouts are also discussed.

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    Article (Published)
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    © 1985 Elsevier. This version of this article is open access and can be downloaded and shared. The original author(s) and source must be cited.
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    • Kaiser, P.K., Guenot, A., and Morgenstern, N.R. (1985). Deformation of small tunnels - IV. Behaviour during failure. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 22(3), 141–152. DOI: 10.1016/0148-9062(85)93228-0.