深埋隧洞应变型岩爆倾向性评估的新数值指标研究

A NOVEL NUMERICAL INDEX FOR ESTIMATING STRAINBURST VULNERABILITY IN DEEP TUNNELS

应变型岩爆是深埋隧洞常见且频发的岩爆类型,严重威胁深埋隧洞施工安全,其破坏位置和程度的准确评估对该类岩爆的防治具有极为重要的工程意义。在系统总结和分析国内外岩爆倾向性数值指标评估方法优势和不足的基础上,从局部能量释放率基本理论出发,提出新的岩爆倾向性评估数值指标,即相对能量释放指数(RERI)。全面地阐述该指标的构建思想和基本原理及其物理意义,并将该指标成功应用于锦屏二级水电站引水隧洞应变型岩爆和加拿大Rm415试验洞脆性破坏等问题分析,验证新指标的合理性和适用性。研究表明,RERI指标能够较为准确地指出高应变型岩爆风险区域和位置,并能相对准确地指出深埋隧洞岩体开挖损伤区的范围,为深埋隧洞应变型岩爆灾害和脆性破坏的评估与防治提供新理论和分析工具。

The strainburst is a common type ofrockburst, 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（RER/）, was proposed. The establishment and the physical meaning of the method were described in detail. The rationality and applicability ofRER/were studied and verified against the strainburst cases occurred in tunnels at Jinping II power station and a brittle failure case occurred in Canadian Rrn415 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. RER/can be utilized as a new theory and an analysis tool to assess the strainburst vulnerability and the brittle failures.