DIAMETER REDUCTION DEVICE OF SEGMENT FOR TUNNEL, TUNNEL LINING STRUCTURE AND FREEZING EXPANSION COUNTERMEASURE METHOD

PROBLEM TO BE SOLVED: To provide a diameter reduction device of a segment for a tunnel, a tunnel lining structure and a freezing expansion countermeasure method, capable of further surely reducing freezing expansion pressure acting on the segment, capable of shortening a construction period and capable of reducing cost.SOLUTION: A diameter reduction device 100 is provided for diametrically reducing a lining diameter D of a segment 12 for constituting a tunnel lining by mutually joining by being juxtaposed in the circumferential direction S and the axial direction of a tunnel inner surface 10, and is provided with pressure adjustment means 22 provided between joints 16 of the segment 12 adjacent in the circumferential direction S and adjusting a diameter reduction quantity of the lining diameter D by changing a separate distance (d) between the joints 16 in response to earth water pressure acting on the segment 12 from the peripheral ground G.SELECTED DRAWING: Figure 1 【課題】セグメントに作用する凍結膨張圧をより確実に低減できるとともに、工期短縮とコストダウンを図ることのできるトンネル用セグメントの縮径装置、トンネル覆工構造および凍結膨張対策方法を提供する。【解決手段】トンネル内面１０の周方向Ｓおよび軸方向に並設されて互いに接合されることによりトンネル覆工を構成するセグメント１２の覆工径Ｄを縮径する縮径装置１００であって、周方向Ｓに隣り合うセグメント１２の継手１６間に設けられ、周辺地盤Ｇからセグメント１２に作用する土水圧に応じて継手１６間の離間距離ｄを変更して覆工径Ｄの縮径量を調整する圧力調整手段２２を備えるようにする。【選択図】図１