Abstract:  To reduce the interaction of the two tunnel boring machines(TBMs) in the extralong tunnels and further realize coordinated, highefficient, and rapid construction, a case study is conducted on a bid section of the North Xinjiang water supply phase Ⅱ project. Then the TBM assembly tunnel structure, belt conveyor mucking, track transportation, and tunnel drainage are analyzed. Finally, some key techniques for highefficient doubleTBM construction, including structural optimization of TBM assembly tunnel, doubledirectional multilevel belt conveyor mucking, comprehensive track transportation, and convergent cascade drainage, are formed based on the construction idea of independent operation and unified management. The application effect show that the optimized structure of the assembly tunnel is reasonable, which meets the needs of synchronous assembly of two TBMs and helps to realize the establishment of key technical systems such as belt conveyors, track transportation, and construction drainage. During tunneling stage, various systems operated well, and the expected goals have been achieved steadily.

Key words: extra long tunnel, open TBM, one tunnel bored by two TBMs, auxiliary tunnel, doubledirectional multilevel belt conveyor mucking, interchangeable rail transit, convergent cascade drainage