Abstract
Underpass tunnels are often constructed on the bottom of railway. For preventing a relaxation of natural ground by excavation, box form roofs are set around the area in which the underpass tunnel will be constructed. However, in some cases, box form roofs are gradually bended on bolted joints by both an earth pressure and railway load. It is needed for constructing underpass tunnels safely to manage the torque of bolts in the box form roof. Torque managements of bolts are a valuable important theme for various engineering fields. It is difficult to estimate an initials axial force of bolts, because the relationships between applied torque and initial axial force are changed and affected by both mechanical properties of materials between a bolts and the surface condition of bolts. In this study, in order to appropriate manage a torque of bolts in constructional materials bended by external forces, several bending tests for full-size box form roof used for underpass tunneling method are conducted. The results are demonstrated that as the torque of bolt is increased, both deflection and aperture are decreased. Furthermore, new evaluating method using FE analysis for this bending problem is developed.
