| Up-close visual inspection has been mandatory and hammer strike test is done as necessary in periodical inspection for all road tunnels in Japan from 2014. Information obtained by inspections should be accurately evaluated in order to diagnose the soundness of tunnel and select proper countermeasures correctly. Defect and deformation mechanisms of the permanent lining of mountain tunnels, such as crack occurrence and development, have not entirely been clarified, and the delamination and spalling of concrete, harming tunnel users, sometimes occurs. Data related to the crack width and stress change of permanent lining were gathered over 10 years and its long-term behavior and durability are discussed. The results provide insights needed to set frequency and methodology of periodical tunnel inspection through the basic behavior of lining, including the cracks over concrete. |
