Abstract
A vertical shaft of the shield tunneling method requires a bearing pile-wall to resist earth pressure at excavation. Then, the part of the pile-wall should be cut at proceeding a shield tunnel. Therefore, the most desirable material property of the shaft is a sufficient resistance against bending moment, and is also easiness to be cut by shear force. For this purpose the authors have developed a hybrid member which consists of a fiber reinforced foamed urethane (FFU) member and a reinforced concrete member. The key of the hybrid member lies in the way how to connect both members. The authors initially proposed three connection methods, such as a mechanical connection, an anchor connection and a flare welding connection. The mechanical behaviors of these three connections were examined experimentally and the anchor connection was found out as the most desirable connection. Finally, the full scale model was tested and was proved to be sufficient for actual use.
