破碎软岩隧道施工期位移控制值的确定及其应用研究

Establishment and application of the deformation during the value for soft rock tunnel in break zone

因破碎区软岩隧道特殊的地质环境条件,在施工中建立一个合理的位移控制体系尤为重要。文章以极破碎区姚渡至广元高速公路工程项目(简称广甘路)中的杜家山隧道为依托,结合隧道特点与洞周位移分布规律,确定了针对该工程软岩隧道的位移控制指标;通过对197个位移监测断面变形正常段、发生异常及险情段位移的统计分析,建立以三台阶+预留核心土法的位移控制基准。结果表明:可将隧道埋深与拱顶沉降作为破碎区软岩隧道以三台阶+预留核心土法的位移控制指标(值),其中埋深≤100m时,拱顶下沉极限位移为260mm;埋深100～200m时,拱顶下沉极限位移为340mm,埋深200～300m时,极限位移为400mm。最后通过杜家山隧道160个断面的运用,共计发现险情与异常情形46个,及时进行加固处理,确保施工安全、顺利、高效进行。

Building a reasonable displacement control system of a soft soil tunnel is important during construction in crushing zones due to special hydrogeologic environment.This paper relays on the Dujiashan tunnel in the project of Yaodu to Guangyuan highway,which for short is the Guang-Gan Road,in an extremely crushing zone.Based on displacement control reference of tunnel at home and aboard,and combined with the characteristics and hole cycle displace distribution law of tunnel,displacement control indexes of soft soil tunnel are determined.According to statistics analysis on displacements of normal sections and abnormal sections and dangerous sections of 197 displacement monitoring sections,displacement control reference is built,whose core is three steps and the reserved core soil method.The results show that tunnel depth and vault displacement can be chosen as displacement control indexes.When the depth is less than 100m,the extreme displacement of vault is 260mm,and when depth ranges between 100m and 200m,the extreme displacement is 350mm,while the depth is more than 200m,the extreme displacement is 420mm.Based on the application in 160 sections of the Dujiashan tunnel,46 abnormal and dangerous sections are found.