METHOD OF FORMING WIDENING PART OF SHIELD TUNNEL

摘要

PROBLEM TO BE SOLVED: To suppress variation in interval between roof shields even if a widening part for shield tunnels varies in cross-sectional size when formed.SOLUTION: A method of forming a widening part for shield tunnels according to the present invention is characterized in arranging a number of small-diameter shield tunnels needed so as to obtain substantially the same arrangement interval with a reference cross-sectional position where the cross-sectional area of the widening predetermined region 3 is maximum at a cross-sectional position smaller in cross-sectional area than the reference cross-sectional position along a cross-sectional contour 11 and also arranging the remainders behind them so that the small-diameter shield tunnels are all arranged at the reference cross-sectional position along the cross-sectional contour 11 of the widening predetermined region 3. Then the small-diameter shield tunnels 5-1 to 5-18 are extended up to the reference cross-sectional position while maintaining an angle position, where arrangement change to a state of the small-diameter shield tunnels along the cross-sectional contour 11 is made, at 0°.