ORIGINAL PAPER The Effect of the Stress Path on Squeezing Behavior in Tunneling Linard Cantieni Georgios Anagnostou Received: 22 January 2008 / Accepted: 30 September 2008 / Published online: 9 December 2008 Ó Springer-Verlag 2008 Abstract The interplay between support systems and the rock when tunneling under squeezing conditions is normally studied by means of two-dimensional analyses. The present paper shows that the underlying plane strain assumption involved in a two-dimensional analysis may lead, under certain conditions, to ground pressure and deformation values that are considerably lower than those produced by stress analyses that take into account spatial effects in the vicinity of the tunnel face. The differences are due to the stress path dependency in the elasto- plastic behavior of the ground and, more specifically, to the inability of the plane strain model to map the actual radial stress history, which involves a complete radial unloading (and, later, a re-loading) of the tunnel boundary over the unsupported span. This inherent weakness of any plane strain analysis is relevant from the design standpoint, particularly for heavily squeezing conditions that require a yielding support. For the majority of tunneling conditions and methods, however, involving as they do the completion of a stiff support within a few meters of the face, the errors introduced by the plane strain assumption are not important from a practical point of view. Keywords Squeezing Tunneling Stress history Stress path Convergence–confinement List of Symbols a Tunnel radius c Ground cohesion d Lining thickness dk 1, 2 Plastic multipliers L. Cantieni (&) G. Anagnostou ETH Zurich, Switzerland e-mail: [email protected] 123 Rock Mech Rock Eng (2009) 42:289–318 DOI 10.1007/s00603-008-0018-9 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by RERO DOC Digital Library
The Effect of the Stress Path on Squeezing Behavior in Tunneling
Jun 04, 2023
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