Some tunnels constructed by the conventional excavation method have defect like an insufficient lining thickness and voids behind the lining. It is thought that the structural strength of defective lining is lower than that of sound lining against the punching shear stress caused by loosening pressure. Therefore, we performed model tests to quantitatively estimate the influence of initial defects on the structural strength of lining under the punching shear stress. We found that defective lining was brittle in its destructing behavior against punching shear stress and the structural strength became smaller than that of sound lining when the lining thickness was about half that of sound lining. We proposed a criterion of countermeasures for tunnel lining against punching shear stress based on these test results.

Copyright (c) 2005 Railway Technical Research Institute