STUDY ON DEFORMATION AND FAILURE BEHAVIOR OF MOUNTAIN TUNNEL LININGS WHICH CONSIST OF VARIOUS MATERIALS

Authors performed model tests and numerical analyses to clarify a limit state of mountain tunnel linings which consist of various materials focused on deformation and failure behavior. It was found that plain concrete lining does not show decreasing of load until it receives large deformation, whereas cracks occur and structural stiffness decreases, and it was found that plain concrete lining has good deformability. It was found that brick lining has smaller structural stiffness and bearing capacity than those of plain concrete lining, and cracks occur between the two beds of bricks after it receives large deformation. It was found that structural stiffness and bearing capacity of short-fiber-reinforced concrete lining are almost same as those of plain concrete lining; however the short-fiber-reinforced concrete lining has good untispalling ability at the part where compressive bending failure occurs. It was found that structural stiffness and bearing capacity of reinforced concrete lining are larger than those of plain concrete lining, and reinforced concrete lining are able to support load after yielding of its rebar, on the other hand, it was also found that shear failure becomes easy to occur by improving ending capacity. 筆者らは，山岳トンネル覆工の限界状態に着目し，種々の材料からなる山岳トンネルの覆工の模型実験や数値解析を行った．無筋コンクリート覆工は，比較的大きな変位まで荷重の低下がなく，アーチ構造の優位性が確認されたが，最大荷重が発生するよりも前の段階で覆工内側に圧ざが生じた．れんが覆工は，無筋コンクリート覆工と比べて剛性や耐荷性能が小さく，変形が大きくなると層間ひび割れが発生することがわかった．短繊維補強コンクリート覆工は，剛性や耐荷性能は無筋コンクリート覆工とほぼ同じであるが，圧ざを生じた箇所の剥落抵抗性に優れていることがわかった．RC覆工は，剛性や耐荷性能は無筋コンクリート覆工に比べて大きくなり，鉄筋が降伏した後も荷重を保持できるが，その一方で，せん断破壊のモードとなりうることがわかった．