Design of Water-conveying Shield Tunnel Crossing Ganjiang River

The difficulties in the design of water-conveying shield tunnels are discussed,with a water-conveying shield tunnel in Nanchang as an example.The loading of the water-conveying shield tunnel is analyzed and the design of the tunnel is described.Main study contents and conclusions drawn are as follows: 1) The design of the alignment,longitudinal profile,segments and shield receiving shaft of the tunnel are studied on basis of the geological conditions.2) The major difference among water-conveying shield tunnels,highway shield tunnels and railway shield tunnels is that water-conveying shield tunnels have internal water pressure.The difficulty in the design of water-conveying shield tunnels is how to determine the internal water pressure.3) The maximum ground water level,the minimum ground water level,the usual internal water pressure and the unusual internal water pressure need to be considered in the design of water-conveying shield tunnels.In this way,the internal force envelope diagram of the tunnel is achieved and the steel bar arrangement is worked out,so as to achieve safe and economic design.4) The water-conveying shield tunnel crossing Ganjiang river in Nanchang is one of the few water-conveying shield tunnels located in rocks built in China,which provides a solution for the construction of small-diameter water-conveying tunnels in the future.