Many shield tunnels have been constructed, in urban and mountainous areas, which should be maintained properly to confirm the structural stability and secure the users’ safety. However, the influence of geological conditions, the fluctuation of water pressure and the difference of lining structure on the mechanical behavior of lining is uncertain in many cases. Also, the inspection method for shield tunnels has not been established due to lack of comprehensive knowledge of critical defects on shield tunnels. In order to examine the above and establish maintenance method of the tunnel by shield tunneling method, we report on the result of the basic behavior of lining by measurement for approximately 18 months and the consideration of the factors behavior. We grasp the temperature inside and outside a tunnel and the displacement of the joint both of linings and segments. The object of measurement is a utility tunnels in urban area by shield tunneling method. The condition is approximately overburden of 25 m, and the geology around the excavated area is the diluvial deposit. Also, alluvial clay accumulated on the upper part, and the natural groundwater level was about 2 m to 5m below the surface. From the measurement results, the fluctuation of temperature in the tunnel was confirmed according to the seasonal change, as well as, the expansion and contraction of the joint of lining and segment. This expansion and contraction was confirmed with the same tendency as the change in temperature although there was a time lag. And the behavior of them in a long cycle of one year was admitted. In addition, we confirmed the fluctuation of the groundwater level in the vicinity of the tunnel, about 10 cm within this measurement period. Influence on the expansion and contraction of the lining was limited within the range of this variation in the diluvial deposit layer and temperature change in the tunnel should be considered when the durability of tunnel is discussed. |