INVESTIGATION OF OPENING AT SIDE WALL OF EXISTENT OPENCUT TUNNEL BASED ON NUMERICAL CALCULATION

This paper investigates the influence of opening at side wall on the members of existent cut-and-cover tunnels by means of 3D FEM (finite element method). The calculation results obtained by 3D FEM was compared with those by 2D frame analysis under the condition that there is no opening at side wall. The influence of opening was investigated based on 3D FEM. The calculation results revealed the change of sectional forces near the opening and the influence of opening width on the values of sectional force. The applicability of conventional methods with 2D frame analysis and 2-direction slab method was also investigated by comparing with the results of 3D FEM. 既設の開削トンネルの側壁に開口を設ける場合を対象に，三次元FEMを用いた検討を行った．まず，開口が無い場合について三次元FEMと二次元フレーム解析による従来の設計計算との比較を行い，三次元FEMが設計計算と整合していることを確認した．つぎに，側壁に開口を設けた場合を対象に三次元FEMによる解析を行い，開口を設けることによる三次元的な応力の変化や開口の幅が及ぼす影響について把握するとともに，開口補強梁を設けた場合の効果を把握した．最後には，実務の設計計算における簡便な検討手法を提案するため，三次元FEMの解析結果を表現できる二次元フレーム解析や二方向スラブの理論を用いた方法を構築した．