CONSTRUCTION METHOD FOR UNDERGROUND WIDENED PART

摘要

PROBLEM TO BE SOLVED: To provide a construction method for an underground widened part that may be implemented safely without excavation.SOLUTION: A construction method for an underground widened part includes the following steps for: removing a segment of a shield tunnel and constructing a starting base for a shield machine used for forming an underground widened part around the shield tunnel; starting a preceding shield machine from the starting base and installing a plurality of preceding shields in a ring form leaving an interval, the preceding shield having a segment for cutting disposed thereon; starting a following shield machine from the starting base and installing a plurality of following shields in a ring form while cutting a part of the preceding shield; forming a water cutoff area on outer periphery of the preceding shield and the following shield; connecting the preceding shield with the adjacent following shield and configuring a ring-form outer shell shield outside of the shield tunnel, thus forming an outer shell for the underground widened part; and excavating inside the outer shell shield after configuring the outer shell shield.SELECTED DRAWING: Figure 2