EFFECTS OF SHAPE ON THE STIFFNESS OF ISOLATION RUBBER FOR CENTER COLUMNS OF TUNNELS

摘要

Reinforced concrete columns supporting the ceiling slab of Daikai subway station, a box tunnel constructed using the cut-and-cover method, totally crumbled down in the 1995 Hyogoken-Nanbu earthquake. Among a variety of tunnel members, the center columns sustaining the weight of overburden soil are the most important key members, and therefore should not be destroyed. Insertion of flexible joints on the upper and/or lower ends of these columns would be a possible measure. This paper presents a possible shape of a column joint that will meet the necessary requirements for the device sustaining a heavy overburden soil mass and reducing the induced shear force and moment. It was shown that a device made of rubber being sandwiched from both right and left sides by the arched steel plates could be a possible shape. Additionally, it was found that the device is able to exhibit its performance without being affected by the overburden load.