| Many shield tunnels have been constructed in urban areas in many countries. They should be maintained properly to confirm the structural stability and to secure the users’ safety. Cracks on secondary lining or water leakage between segmental joints are frequently-found defects. Width of cracks and joint opening are typically affected by seasonal temperature change. Periodicity of the width is therefore one of the most important factors to find the cause of the defects and to select a proper countermeasure against the defects to secure the sustainability of structure. In this study, two actual shield tunnels are used to measure such items as air temperature, concrete temperature, humidity in the air, width of crack, opening width of segmental joint, and deformation of the tunnel continuously throughout more than three years. Relationships between these items and range of the seasonal change are discussed in the paper. Major conclusions include that expansion and contraction has the same tendency as the change in temperature with annual change, while a qualitative time lag exists. |
