软弱千枚岩地层围岩亚分级及支护方式研究

Research on supporting methods and sub-classification of complex phyllite rock layer in Baojiashan tunnel

包家山隧道穿越的千枚岩地层工程地质复杂,断层多,岩体性质变化大,围岩稳定性差,遇水极易软化。依据现有围岩分级的施工方法进行施工,施工中多次出现掉块、坍塌现象。在确定包家山隧道千枚岩基本水理性质基础上,依据《铁路隧道设计规范》(TB10003-2005),运用国标《工程岩体分极标准》(GB50218-94)中岩体基本质量指标(BQ),对隧道IV、V级千枚岩进行了较为细致的分级,将IV、V级围岩分为两个亚级,建立了千枚岩围岩施工阶段亚级分级方法。获得了不同亚级的包家山千枚岩隧道施工方法,并运用该亚分级对应的施工方法进行施工,实现了日进度达到3.75 m,保证了施工安全和施工进度。

The geology of the region which Baojianshan tunnel crossed through was very complex. The layer was consisted of broken phyllite which was easily softened with water. The rock mass had collapsed several times while excavation by the construction methods which designers offered. In this article, the sub-classification of phyllite was established according to State Standard Classification of Rock and Designing Standard of Railway Tunnel. Based on this sub-classification, a series of construction methods in phyllite were set up eventually. And Baojiashan tunnel was sueeessfuUy built using the construction methods mentioned above.