涌水大跨分岔式隧道施工关键技术研究

Research on Key Technology for Construction of Gushing Large-span Bifurcation Tunnel

以阳安二线直通线包湾村隧道工程为背景,介绍了一套完整的分岔大跨隧道施工技术,对开挖方法确定、分岔段及渐变段施工等关键控制技术进行了详细阐述。通过对加宽断面处数值模拟,分析了加宽断面开挖时的隧道围岩变形、衬砌结构应力分布。实践表明:断面加宽处面积突然增大,施工对围岩的扰动区域增大,应力释放过程加快,释放的围岩压力增加,导致累积变形量增大,衬砌受力增大;对于分岔大跨度,在环境复杂、地质条件差的情况下采取适当的地层加固措施,不同断面的合理渐变、超大断面的合理分块、保留临时支撑施作二次衬砌等技术切实有效。

Taking Baowancun Tunnel project of Yang'an Second Line Direct Line as the background,a complete set of bifurcation large-span tunnel construction technology is introduced,and key control technologies such as the determination of the excavation method,the construction of the bifurcation section and the transition section are described in detail.And through the numerical simulation of the widened section,the tunnel surrounding rock deformation and the stress distribution of the lining structure when the widened section is excavated are analyzed.Practice shows that the cross-sectional area suddenly increases at the widening of the cross-section,the area of disturbance to the surrounding rock by the construction increases,the stress release process is accelerated,and the released surrounding rock pressure increases,resulting in an increase in the cumulative deformation and an increase in the force on the lining;for a large span,appropriate stratum reinforcement measures are taken in the case of complex environment and poor geological conditions,reasonable gradation of different sections,reasonable division of super-large sections,and techniques such as retaining temporary supports for secondary lining are practical and effective.