Abstract: The mechanized construction method for connecting passages can be divided into shield and pipe jacking methods. To clarify the difference between mechanical and freezing methods, the structural characteristics and safety, environmental influence, construction efficiency, and energy consumption of the 21 connecting passages of shield tunnel of Ningbo rail transit line 4 are analyzed.Analytical results demonstrate the following. (1) The main tunnel structures constructed using different construction methods are uniform to guarantee the standardization of the main tunnel structures. (2) Various construction methods can meet relevant structural functions, structural safety, and environmental requirements. (3) The convergence deformation of the main tunnel obtained using the mechanical method is smaller than that obtained using the freezing method, which promotes structural safety. (4) Under the same conditions, the mechanical method requires approximately half the time of the freezing method. Moreover, the power consumption per linear meter of connecting passages obtained using the mechanical method is onetenth of that obtained using the freezing method.

Key words: rail transit, connecting passage, shield method, pipe jacking method, freezing method, settlement deformation, construction efficiency