Key techniques for group construction of deep-buried and super-long water transfer tunnel by TBM

The Xi-Er, Kashi-Shuang and Shuang-San tunnels of the 2^nd stage water transfer project in the northern areas of Xinjiang Uygur Autonomous Region are totally 516.19 km in length, and they are designed to be constructed section by section using 18 TBMs. Among which, the Kashi-Shuang tunnel, with a single tunnel 283.27 km in length, is currently the longest water transfer one to be constructed in the world. It is characterized by deep burial, super length and group construction of TBM. Based on the geological features and conditions of the research areas as well as large quantity of geological surveys and test data, the main engineering geological problems in deep-buried and super-long tunnels are investigated, and the combined construction scheme of TBM and drilling-blasting method is proposed. The highlights, difficulties and key techniques in the construction of the project are preliminarily analyzed and discussed, including sub-tunnel construction of deep-buried tunnel and selection and layout of TBM-entering tunnel patterns, section-by-section construction of super-long tunnel and optimization of TBM tunneling schemes, group construction of TBM and high-efficient operation and management of the auxiliary system, forecast of geological disasters and prevention and control of risks, and deformation control of soft rock and safe tunneling in fault zones. It may provide technical support for the design and manufacturing of TBM and the construction of large interregional water diversion and long water transfer projects.