In this project, a box (underground structure) was constructed on an approximately 1.6km section of the Tokyo Gaikan Expressway located in Ichikawa City, Chiba Prefecture. The construction area was a two-layer, four-row steel shell structure approximately 19m high and 43m wide, spanning a length of 2m (4 rings) in the area adjacent to the Keisei Line.
Support for special structures
The joint bolts (M27) between the rings often interfered with the rib plate, making it impossible to install with existing tightening equipment, and there were concerns that the tightening of about 4 bolts would be a bottleneck and affect the process. We developed and newly created a special small wrench suitable for the site. In addition, to ensure accuracy, we developed and used an SC structural box temporary assembly simulation system based on the steel bridge temporary assembly simulation system (numerical temporary assembly system CATS).
Construction plans and on-site innovations
Unlike regular steel bridges, the management items such as lengthwise, perpendicular, vertical, and securing the interior space of the box were diverse and complex, so we installed fittings to prevent beams from falling, erection guide fittings, etc., and adjusted the shape. Through consistent management from the construction planning stage to production reflection and on-site construction, we were able to keep the error in the ring extension direction to -50mm against the tolerance of ±5mm.