Abstract: The negative ring assembly is one of the key construction processes in shield launching. In order to solve the construction problems such as negative ring assembly difficulty during shield launching, irregular assembly process and large deviation of assembly size, theoretical study, threedimensional simulation, numerical calculations, etc. are used to study the construction process and roundness fitting inspection methods of fine assembly of superlarge diameter shield negative ring by taking Nanjing Heyan Road Rivercrossing Project for example. The assembly positioning method and related construction measurement content of negative ring are emphatically studied; the control points in the construction process are described; the selection method of locating feature points, the control method when tubes are rolled out, the method to reduce the influence of tube sinking, the control standards for tube assembling, etc. are summarized; and thus a calculation method of flatness of the superlarge diameter shield tubes is formed. The applicable results of the study (to the negative ring assembly process of Heyan Road Rivercrossing Tunnel Project) show that: the construction process is smooth, the accuracy of the negative ring assembly and the control of the roundness are higher than the requirements of the design and specification, and the dislocation and ellipticity are reduced to the maximum extent, which greatly improves the forming quality of the tubes.

Key words: superlarge diameter shield, negative ring assembly, assembly positioning, assembly refinement, tube flatness detection