A NOVEL NUMERICAL INDEX FOR ESTIMATING STRAINBURST VULNERABILITY IN DEEP TUNNELS
QIU Shili,FENG Xiating,JIANG Quan,ZHANG Chuanqing
(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)
Abstract:The strainburst is a common type of rockburst,which frequently occurs in deep tunnels and may evoke severe threats to safe tunnelling. From the engineering viewpoint,it is essential to obtain a relatively accurate assessment on the location and the damage effect of rockburst. A comprehensive review and comparison was presented regarding the advantages and disadvantages of the proposed numerical indexes assessing the strainburst vulnerability. Based on an improvement on the theory of local energy released rate(LERR),a novel numerical index,namely the relative energy release index(RERI),was proposed. The establishment and the physical meaning of the method were described in detail. The rationality and applicability of RERI were studied and verified against the strainburst cases occurred in tunnels at Jinping II power station and a brittle failure case occurred in Canadian Rm415 test tunnel. RERI not only accurately indicates the potential failure location and the high risk region,but also quantifies the damage zone of rock mass excavation induced by high stresses. RERI can be utilized as a new theory and an analysis tool to assess the strainburst vulnerability and the brittle failures.
VAN ANTWERPEN H E F,SPENGLER M G. The effect of mining-related seismicity on excavations at east Rand proprietary mines,limited[C]// Proceedings of the First International Symposium on Rockbursts and Seismicity in Mines. Johannesburg:SAIMM,1982:235-243.
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