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Plasticity solutions for soil behaviour around contracting cavities and tunnels
Author(s) -
Yu H.S.,
Rowe R.K.
Publication year - 1999
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/(sici)1096-9853(199910)23:12<1245::aid-nag30>3.0.co;2-w
Subject(s) - geotechnical engineering , stress path , plasticity , mechanics , hardening (computing) , plane stress , stiffness , softening , effective stress , soil water , geology , perpendicular , mohr–coulomb theory , anisotropy , stress (linguistics) , materials science , structural engineering , engineering , geometry , finite element method , physics , mathematics , composite material , soil science , linguistics , philosophy , layer (electronics) , quantum mechanics
The action of tunnel excavation reduces the in‐situ stresses along the excavated circumference and can therefore be simulated by unloading of cavities from the in‐situ stress state. Increasing evidence suggests that soil behavior in the plane perpendicular to the tunnel axis can be modelled reasonably by a contracting cylindrical cavity, while movements ahead of an advancing tunnel heading can be better predicted by spherical cavity contraction theory. In the past, solutions for unloading of cavities from in‐situ stresses in cohesive‐frictional soils have mainly concentrated on the small strain, cylindrical cavity model. Large strain spherical cavity contraction solutions with a non‐associated Mohr–Coulomb model do not seem to be widely available for tunnel applications. Also, cavity unloading solutions in undrained clays have been developed only in terms of total stresses with a linear elastic‐perfectly plastic soil model. The total stress analyses do not account for the effects of strain hardening/softening, variable soil stiffness, and soil stress history (OCR). The effect of these simplifying assumptions on the predicted soil behavior around tunnels is not known. In this paper, analytical and semi‐analytical solutions are presented for unloading of both cylindrical and spherical cavities from in‐situ state of stresses under both drained and undrained conditions. The non‐associated Mohr‐Coulomb model and various critical state theories are used respectively to describe the drained and undrained stress‐strain behaviors of the soils. The analytical solutions presented in this paper are developed in terms of large strain formulations. These solutions can be used to serve two main purposes: (1) to provide models for predicting soil behavior around tunnels; (2) to provide valuable benchmark solutions for verifying various numerical methods involving both Mohr–Coulomb and critical state plasticity models. Copyright © 1999 John Wiley & Sons, Ltd.