Middle Route of South-to North Water Transfer Project is the longest water transfer canal in the world, crossing four river basins, namely, Yangtze River, Huai River, Yellow River and Hai River, with an annual transfer capacity of 9.5 billion m3 water to Beijing, Tianjin and other northern cities of China. The total length of main transfer canal is about 1427km, including over 1800 structures such as shield boring tunnel crossing Yellow River and the largest aqueduct in the world, etc.
CISPDR performed the general technical control and management of the whole project and also undertook survey and design for such important structures as the heightening of Danjiangkou dam, water source project for the canal, and the underwater transfer tunnel across the Yellow River.
The underwater transfer tunnel across the Yellow River is a critical component for the whole project. It is arranged in dual lines of shield boring tunnels crossing the overburden of riverbed, with ID of 7m and 4250m for each tunnel. Due to the complicated geological conditions, measures must be taken on the technical difficulties of the riverbed shifting, severe scouring & silting, seismic liquefaction of sandy soil, soft soil subsidence from earthquake, tunnel seepage, stability of surrounding soil, safety of pressure water transmission and long term operation etc. The design scheme of “double lining prestressed concrete structure” proposed by CISPDR for the shield boring tunnels has resolved key technical issues regarding super-deep work shaft, antiseismic capability of structure in soft area, safety monitoring and long distance data transmission in long tunnels, long distance shield boring of underwater pressure tunnel, etc, thus ensuring the smooth progress of the project. It is the first application of this new technology on the shield boring traffic tunnel or hydraulic tunnel. At present, shield boring for both lines of tunnels crossing the Yellow River has been completed.