| 摘要 |
PROBLEM TO BE SOLVED: To provide a timbering skeletal structure which enables safe tunnel construction without protection thereof by soil improvement even on a crush zone or fragile ground. SOLUTION: In lining a tunnel which is constructed in a mountain or on consolidated earth, an invert portion is formed of blocks and an upper half portion is formed of timbering. The upper half timbering is comprised of a plurality of main girders 1, 2, a net 8 arranged on the natural ground side, filler blocks (rods) 4 which maintain an interval between the main girders and back up the net 8, and joint plates 13. According to the timbering structure, first both the main girders are built at a narrow interval, but as an excavator is driven, the main girder at a location closer to a cutting face is drawn by the excavator to expand the interval, followed by spreading the net 8. After the interval between the main girders is expanded to a predetermined span, the filler blocks (rods) 4 are fixed to the ground, to thereby complete construction of the timbering structure. COPYRIGHT: (C)2004,JPO
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