ABSTRACT

A growing number of shield tunnel projects have been implemented for constructing road tunnels with an outer diameter of as large as 11 to 13 m and without any secondary lining. With recent technological advancements, segmental linings have become thinner and lining rings have become wider to reduce construction costs. Then, safety margin against loads during construction, which were difficult to handle quantitatively in conventional design processes, has been reduced and lining damage is more likely to be caused.