丽香铁路玄武岩隧道大变形段施工控制技术

Construction Control Technology for Large Deformation Section of Basalt Tunnel on Lijiang-Shangri-La Railway

为有效控制丽香铁路三叠系玄武岩大变形的突出难题,在分析大变形机制及原因的基础上制定支护措施,并进行现场试验,对大变形段的原位强度、松动圈、矿物成分、地应力大小、变形特征、初期支护及二次衬砌内力等进行了测试。总结出以下措施可有效控制玄武岩大变形:1)加大边墙轮廓曲率及预留变形量;2)加大初期支护钢架型号及加长边墙系统锚杆;3)缩短初期支护钢架封闭时间;4)施作二次衬砌期间控制初期支护变形速率为1~2 mm/d。

During the construction of Lijiang-Shangri-La Railway, large deformation of Triassic basalt is very serious. Hence, the deformation mechanism and causes are analyzed; and the supporting measures are determined. And then field test is carried out. Finally, tests are carried out on in-situ strength, loose zone, mineral compositions, ground stress, deformation characteristics and internal forces of primary support and secondary lining of large deformation section. It is concluded that the following measures can effectively control the large deformation of basalt： （1） Increasing the curvature of sidewall and amount of reserved deformation. （2） Increasing the primary support steel frame model and lengthening the sidewall system bolt. （3） Shortening the closing time of primary support steel frame. （4） Controlling the primary support deformation velocity within 1-2mm/d when carrying out secondary lining.