2011年《岩石力学与岩土工程学报》英文版第1期电子版|Journal of Rock Mechanics and Geotechnical Engineering

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Quantitative analysis of rockburst for surrounding rocks and zonal disintegration mechanism in deep tunnels

Qihu Qian¹^*, Xiaoping Zhou²

¹Engineering Institute of EngineeringCorps, PLA University of Science and Technology, Nanjing, 210007,China

²School of Civil Engineering, Chongqing University, Chongqing,400045, China

Received 21 December 2010; received in revised form 25 January 2011; accepted 5 February 2011

Abstract:Rock masseswithoutpre-existing macrocrackscan usually beconsidered as granular materials with only microcracks. During theexcavation of the tunnels, microcracks may nucleate, grow and propagate through the rock matrix; secondary microcracks 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. Based on non-Euclidean model of the discontinuous and incompatible deformation of rock masses, the distribution of stresses in the surrounding rock masses indeep tunnels is fluctuant or wave-like. The stress concentration at the tips of microcracks located in vicinity ofstress wave crest is comparatively large, which may lead to the unstable growth and coalescence of secondary microcracks, and consequentlythe occurrence of fractured zones. On the other hand, the stress concentration at the tips of microcracks located aroundstress wave trough is relatively small, whichmaylead to the arrest of microcracks, and thus the non-fractured zones. The alternate appearance of stress wave crest and trough thus may induce the alternate occurrence of fractured and non-fractured zones in deep rock masses. For brittle rocks, the dissipatedenergy of microcrack growth is small, but the elastic strain energy stored in rock masses may be larger than the dissipatedenergy growthsof pre-existing microcracks and secondary microcracks. The sudden release of the residual elastic strain energy may lead to rockburst. Based on this understanding, the criteria of rockburst areestablished. Furthermore, the relationship between rockburstsand zonal disintegration in the surrounding rock massesaround deep tunnels is studied. The influencesof the in-situ stressesand thephysico-mechanical parameters on the distribution of rockburst zones and the ejection velocity of rock fragments areinvestigated in detail.

Key words: underground tunnel; rockburst; zonal disintegration; non-Euclidean model

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