EVALUATION OF SOUNDNESS IN THE LONG UNDERSEA TUNNEL BASED ON LONG TERM CONVERGENCE MEASUREMENT AND MEASUREMENT OF LINING STRESS

Abstract

 Seikan Tunnel is in special condition that is under the seabed. So the lining concrete is not affected by water pressure directly as the surrounding areas of the tunnel were grouted the waterproof zone.
 In this paper, the current soundness of the lining is evaluated by focusing long term convergence measurement, visual inspection and measuring stress of lining, for the purpose of grasp of the long term properties of the tunnel and proper maintenance. As the result, in most cases, the displacement is small. On the other hand, in some of section which has been measured displacement relatively large, lining stress is basically equal to the design strength. However it is smaller than compression strength. In addition, we also evaluate soundness of the future of lining, by consideration of forecasting displacement and stress.