秦岭特长隧洞超埋深强构造应力大变形处理技术研究

Study on technologies for treatment of large deformation of extra-long Qinling Tunnel under super buried depth and strong tectonic stress

引汉济渭秦岭特长输水隧洞全长81.779 km,隧洞穿越秦岭岭南中低山区,地质条件极其复杂,断裂构造极为发育,且具有强构造应力。受复杂地质条件和地质构造的影响,秦岭隧洞1~#勘探试验洞主洞段施工中发生了不同程度的大变形,原设计围岩类别为Ⅲ类,实际施工过程中已经达到Ⅳ类和Ⅴ类,初期支护完成后变形严重。多处变形量超过10 mm/d,局部最大变形量达到了69 cm,给施工带来了极大的困难。对发生大变形段采取了二次套拱、加长锚杆、径向注浆、初支拆换、二次衬砌加强等措施进行控制。今后大变形段设计施工过程中,应通过加强超前地质预报与监控量测、提高支护设计参数、加大预留变形量来预防大变形的发生。

With the total length of 81. 779 km,the extra-long Qinling Water Delivery Tunnel for Hanjiang River-to-Weihe River Water Diversion Project passes through the middle-low mountainous area of the South of Qinling Mountain under a complicated geological condition; i. e. over-developed fracturing structure and strong tectonic stress. Under the impacts from the complicated geological condition and geological structure therein,the large deformations with various scales occur during the construction of the main tunnel of the No. 1 exploration-test tunnel for the construction of Qinling Water Delivery Tunnel,for which the original design classification of the surrounding rock is Class III,but it reaches Class IV and Class V during the actual construction,thus deformation is quite serious after the completion of the initial support. The deformation amounts at many locations are over 10mm/d and the maximum local deformation amount reaches 69 cm,and then the deformation brings great difficulty to the construction. For those largely deformed tunnel sections,the control measures,such as secondary cover-arch,prolonged anchor rod,radial grouting,secondary lining,etc.,are adopted. During the design and construction of the largely deformed tunnel sections in the days to come,the large deformation must be prevented through strengthening the advanced geological prediction and monitoring survey,raising the design parameters of support and enlarging reserved deformation amount.