Research On Key Technologies For Rapid Construction Of Pre-stressed Concrete In Long-distance And Deep-buried Water Conveyance Tunnels

The Yellow River Tunnel of the South-to-North Water transfer Project is buried at the bottom of the Yellow River bed with a minimum buried depth of 23 m and a total length of 4250 m.The foundation of most of the holes is full sand layer or upper sand soil layer,and it is a double-layer composite lining structure of prestressed concrete of shield assembled pipe piece geogrid drainage layer.Its design principle is "structure union," Independent function "-lining withstands internal water load,outer lining withstands external soil and water load." The structure is used for the first time at home and abroad,its ultra-thin wall structure,large curvature,large tonnage prestressed ring anchor construction at present in the domestic and foreign no mature construction experience can be used for reference.Based on the project of prestressed concrete in the middle line of Yellow River tunnel of South-to-North Water transfer Project,material transportation,construction quality control of ultra-thin lining concrete and precision control of embedded parts are studied.The construction quality control of large curvature and large tonnage ring anchor prestressed tensioning,the concrete shape control,the construction organization of high construction strength,and the key construction technology of ultra-thin ring anchor prestressed concrete for deep buried ultra-long water conveyance tunnel are summarized.So as to ensure the high impermeability of concrete,the permeability of drainage system,the uniformity of tensile force of the whole structure,and the durability of anchor cable.The research results are applied to the whole construction process of the project and ensure that the middle route project of South-to-North Water transfer Project is put into operation on schedule,with high quality and safety.