Development of divergence construction technology for deep road tunnels

摘要

In recent years, the need for tunnel constructions at greater depths using shield tunneling is increasing for further tunnel projects in urban areas in Japan. In constructing divergence portions with main tunnels at greater depth, conventional methods such as cut and cover may not be appropriate due to the high cost of construction and the considerable influence on the surroundings.rnThe authors developed the new methods where the divergence portion and emergency parking zone from the pre-excavated main shield tunnel are constructed without any work from the ground surface.rnThe method to construct the divergence portion is called the Expandable and Shrinkable Tube Method for Junctions (ES-J method), and the method to locally expand the width in small lengths for emergency parking zones, etc., is called the Segment Expansion Method by Excavation (Seg-Jet method). This paper gives an outline of the ES-J method and Seg-Jet method, and their development technologies.