Abstract:

Rectangular crosssection shield tunneling, as a new tunnel construction method, has the advantage of more effective space usage ratio. It can be used where shallow, longdistance and curved tunnel is to be constructed. Large rectangular crosssection shield tunnel provides an alternative construction mode for connection tunnels and will have a wide application prospect. In the paper, Hongqiao Linkong 11-3 connection tunnel project in Shanghai is described, in order to discuss the difficulties in the design of large rectangular crosssection shield tunnels. The internal force analysis and design method of the tunnel are discussed in detail. The study contents and some conclusions are drawn as follows: 1) Due to the rectangular shape, the joint of the tunnel needs to endure more moment and shear force. Bolt group can be used to meet the forcebearing requirement of the joint. 2) The steel box is the primary bearing member of the adopted composite segment. Deep bolt holes can be designed to solve the installation problem of the bolts. 3) The grouting pressure remarkably affects the distribution of the internal force of the tunnel. The reasonable value and distribution of the grouting pressure determine the economy of the tunnel lining. 4) The load tests made on the segment verifies that the composite segment adopted can meet the requirements of the project.

Key words: rectangular shield, shield tunnel, composite segment, grouting pressure, structural performance