| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost of construction work by simplifying the base isolation structure of the joint between a vertical shaft and a shield tunnel. SOLUTION: A segment 1a is projected inside of a vertical shaft skeleton 10a at the pit mouth 7 of a shield tunnel T, and an insulating layer 8 is provided on the outer peripheral surface of a segment 1a of the pit mouth 7. Also, concrete 9 for joining the vertical shaft skeleton 10a is placed on the outer periphery of the insulating layer 8 and a base isolation structure forming a base isolation layer I is constructed in a gap between the segment 1 of the shield tunnel T and the ground 11. In that case, the base isolation layer I formed on the side closer to the ground 11 than to the vertical shaft skeleton 10a constitutes the base isolation structure whose length is determined by behavior during an earthquake in a direction perpendicular to the axis of the shield tunnel. Further, a slip type segment S fitted with a material 2 which can be separated or slid between the outer peripheral surface of the segment 1 and a backfilling material 3 by the action of a small shearing force is disposed in front of the base isolation structure to provide a slip type base isolation structure which causes slip between the backfilling material 3 and the slip type segment S during an earthquake.
|
