公路隧道局部塌方洞段的围岩稳定性评价

结合某公路隧道工程，以现场地质调查和监测资料为基础，在结构面发育且可能发生大规模塌方的围岩洞段，根据现场实际统计的优势结构面产状，采用关键块体理论、非连续变形方法（DDA）首先确定围岩主要的失稳破坏模式，然后运用连续介质分析程序FLAC，在DDA方法确定的围岩实际变形破坏塌方形态的基础上进行计算分析，评价围岩的整体稳定性及加固措施的有效性。分析表明，围岩破坏的主要模式为受结构面控制的局部块体的失稳，工程开挖后围岩不会发生大变形，这与实际情况基本一致，为安全施工提供了保证。采用非连续变形方法和连续介质计算相结合的分析方法对隧道工程塌方稳定性进行研究，取得了较好的效果，研究方法和经验可为类似工程参考并借鉴。

Research on surrounding rock stability in local collapse section of highway tunnels

Combined with a mountain tunnel project in Hunan province and based on the practical geological analysis and monitoring data, the basic failure mode of surrounding rock is established firstly by key block theory and the discontinuous deformation analysis(DDA) according to the real joint occurrence in the jointed and serious collapse section of the tunnel; and then based on the collapse mode by DDA, the surrounding rock stability is analyzed; and an evaluation for designed reinforcement scheme is made by continuous medium analysis program FLAC; it indicated that the main failure mode of surrounding rock is limited to local block instability controlled by joints and with no possibility of large deformation, which is in accordance with the practice very well so as to provide the assurance for the safety construction. The proposed method of combining discontinuous deformation analysis and continuous medium method for the collapse problem analysis, has acquired satisfying results so as to provide a good reference for other similar projects.