秦岭输水隧洞TBM段初始地应力场分布特性研究

Study on Characteristics of Geostress Field in the TBM Excavation of Qinling Water Conveyance Tunnel

针对引汉济渭工程秦岭输水隧洞大埋深、高地应力容易引发软岩大变形工程灾害的问题,首先对隧洞工程区的构造应力场进行定性分析,然后结合现场地应力测试数据,对TBM施工段进行三维地应力场反演分析,研究秦岭软岩隧洞初始地应力场的分布特征和规律,以指导设计施工。研究结果表明:(1)秦岭输水隧洞区内现今最大水平主应力的优势作用方向为NW向。(2)数值模拟可较好的反演输水隧道地应力分布特性,隧洞高程处的地应力场总体以水平构造应力为主,主应力方向为NNW~NWW向。断层破碎带两侧出现应力集中现象。(3)典型软岩洞段(桩号K51+597)附近以水平构造应力为主,水平应力方位为NW31.4°,最大水平主应力32.73 MPa。该里程处,隧道拱顶附近易发生变形破坏。

To deal with the problem of that the engineering disasters of large deformation,are prone to be caused by the buried depth and high geostress of Qinling Water Conveyance Tunnel,the qualitative analysis of the tectonic stress field in the tunnel engineering area was carried out,and then the 3-D geostress field inverse analyses of the TBM construction section were made based on the in-situ geostress test data for studying the characteristics and law of the initial geostress field of Qinling Water Conveyance Tunnel.so that guide design and construction.The study result shows that the direction of the maximum horizontal principal stress stabilizes to EW in the Qinling Water Conveyance Tunnel area.The geostress distribution of Qinling Water Conveyance Tunnel can be better inversely analyzed by the numerical simulation concerned.The in-situ stress field at the elevation of the tunnel is mainly dominated by horizontal tectonic stress,and the direction of the principal stress is NNW~NWW.Stress concentrations occur at both the sides of fault zones with the increase of stress.In the K51+597 section,the horizontal tectonic stress is dominant,the horizontal stress orientation is NW31.4°,and the maximum horizontal principal stress is 32.73 MPa.Deformation destruction is likely to occur near the tunnel vault because of the in-situ stress.