This technical paper aims to clarify the relations between the results predicted by plane strain modelling and the solutions given by 3-d analysis, for a circular tunnel driven in a homogeneous, isotropic, elasto-viscoplastic medium. It presents the results of a nonlinear axisymmetric finite element simulation of tunnelling in a rock mass, which investigates the stress and displacements behind an advancing tunnel face. All the results obtained from the 3-d modelling have been compared with the related 2-d model of similar mesh and material properties. The computational results disprove the widespread assumption that 2-D numerical analysis overpredicts tunnel convergence; such analysis can lead to a significant underestimation error, when a 2-d modelling of a tunnel excavation is used, especially in the prediction of ultimate unlined tunnel convergence. The authors suggest a simple approach for approximating the difference between the 2-d predictions and the more accurate 3-d predictions, although its function and parameters need to be investigated further; corrections of this sort can be obtained by understanding the mechanism of stress redistribution and the influence of the excavation sequence in three dimensions


  • English

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  • Accession Number: 00487480
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Sep 30 1989 12:00AM