地質不良区間における山岳トンネルの地震被害メカニズム  [in Japanese] SEISMIC DAMAGE MECHANISM OF MOUNTAIN TUNNELS IN POOR GEOLOGICAL CONDITIONS  [in Japanese]

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Abstract

山岳トンネルは一般に地震に強い構造物といわれているが,地震の規模や震源からの距離によってはひび割れや圧ざなどの被害を生じることがある.筆者らは,山岳トンネルの地質不良区間での地震被害に着目し,トンネルが地震被害を受けるメカニズムやトンネルが有する耐震性能を明らかにするために模型実験,数値解析により研究を行った.その結果,載荷方向や構造条件を変化させた模型実験により実際の地震被害を再現することができた.また,背面空洞により変状が生じやすくなること,インバートによりトンネルの剛性が向上すること,インバートがある場合は剛性の増加により覆工の負荷が増加するため,大きな変位が予想される場合は負荷を抑制するための対策が必要となることがわかった.

  Mountain tunnels are generally thought to be less susceptible to seismic damage. However, tunnels often suffer seismic damages such as cracks and compression failure depending on the magnitude of the earthquake and the distance from the epicenter. Authors paid attention to the seismic damage of tunnels in poor geological conditions and performed model tests and numerical analyses to clarify the mechanism of seismic damage to tunnels as well as the aseismic performance of tunnel lining. It was revealed that actual earthquake damage was able to be reproduced by the model tests, in which loading conditions and structural defects were modeled. From the model tests and numerical analyses, it was found that the void above the lining have negative effects on the aseismic performance. The tunnel rigidity can be effectively increased by constructing the invert, resulting in the reduction of tunnel deformation, especially heaving at the invert. However, as the stress in the lining is also increased by the invert when large ground displacement is expected, another countermeasure is necessary to prevent the failures caused by the overstress of the lining.

Journal

  • Doboku Gakkai Ronbunshuu C

    Doboku Gakkai Ronbunshuu C 65(4), 1045-1061, 2009

    Japan Society of Civil Engineers

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