引汉济渭秦岭隧洞TBM卡机脱困分析

Analysis on TBM jamming release of the Qingling Tunnel for Hanjing-to-Weihe River Valley Water Diversion Project

本文以引汉济渭秦岭隧洞TBM卡机段为研究对象,采用现场监测和数值模拟相结合的方法,分析了脱困施工条件下围岩变形、钢架受力等特征规律。结果表明:采用控制性人工开挖和及时新增支护,护盾至撑靴之间换拱卸荷对隧洞岩体的扰动在可控范围;受临近原拱架扩挖拆除影响,钢架顶部应力呈增长状态,增长速率随时间逐步衰减;随着隧洞的超前扩挖,K51+592.3处顶拱变形量较大,围岩变形最大值在紧邻拱顶的两侧位置,顶拱区域两侧围岩塑性区深度较大;TBM完成脱困正常开挖后,锚杆受力值小于设计值,二衬浇筑完成后钢筋应力基本稳定。

In this paper,the TBM jamming section of the Qinling Tunnel for Hanjiang to Weihe River Valley Water Diversion Project is taken as the research object.By combining field monitoring and numerical simulation,the characteristic rules of the surrounding rock deformation and steel frame stress are analyzed under the releasing condition.The results show that the disturbance to the rock mass of the tunnel,which is caused by the arch exchange unloading between shield and support boots,is in a controllable range by using the controlled artificial excavation and timely support.Under the influence of expanding excavation and removal of the adjacent original arch frame,the stress at the top of the steel frame increases,and the increasing rate gradually decays with time.With the advance expansion of the tunnel,the deformation of the arch apex at K51+592.3 is large,and the maximum deformation of the surrounding rock is on both sides of the arch apex.The depth of the plastic zone of the surrounding rock on both sides of arch apex area is large.After the TBM is released and the excavation is normal,the value of the stress is less than the design strength of the bolts,and the reinforcement stress is basically stable after the secondary lining pouring is completed.