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Abstract Rock masses without pre-existing macrocracks are considered as granular materials with only microcracks. During excavation of tunnels，microcracks may nucleate，grow and propagate through rock matrix；secondary micrcracks may appear，and discontinuous and incompatible deformation of rock masses may occur. The classical continuum elastoplastic theory is not suitable for analyzing discontinuous and incompatible deformation of rock masses any more. A new non-Euclidean model is established based on free energy density，the equilibrium equation and the deformation incompatibility condition，where effects of the half length and density of microcracks on scalar curvature and the self-equilibrated stresses in deep rock mass are investigated. Stress fields in the surrounding rock masses around a deep circular tunnel are determined，which are the sum of elastic stresses and the self-equilibrated stresses determined by the scalar curvature. Due to the self-equilibrated stresses，the distribution of stresses in the surrounding rock masses around deep tunnels is obviously fluctuant or wave-like when the half length and density of microcracks are large，while the distribution of stresses in the surrounding rock masses around deep tunnels is not obviously fluctuant or wave-like when the half length and density of microcracks are small. The stress concentration at the tips of microcracks located in vicinity of stress wave crest is comparatively large，which may lead to the unstable growth and coalescence of secondary microcracks，and consequently the occurrence of fractured zones. On the other hand，the stress concentration at the tips of microcracks located around stress wave trough is relatively small，which may lead to arrest of microcracks，and thus to the non-fractured zones. The alternative appearance of stress wave crest and stress trough thus may induce the alternative occurrence of fractured and non-fractured zones in deep rock masses. The influences of the density and half length of microcracks on zonal disintegration and self-equilibrated stresses are investigated in detail by using numerical simulation.
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Received: 19 November 2012
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2013, Vol. 32 
