Estimation of rock load for the design of 2-arch tunnel lining

초록

In this study, the existing methods proposed to estimate relaxed rock load due to a tunnel excavation are compared and analyzed. Also a new approach, by which the stress relaxed zone around an excavated tunnel periphery can be systematically estimated, was suggested for the design of 2 ?arch tunnel lining. To this end, local factors of safety are calculated from the redistributed stresses after the excavation of a tunnel. The height of the relaxed rock load is inferred based on the assumption that the stress relaxed zone might coincide with the region corresponding to the local safety factor of 2.0 or 3.0. The new approach proposed in this study has the advantage of estimating the height of rock load regardless of the shape of a tunnel and the ground conditions. Since the height of the relaxed rock load is estimated from the local factor of safety, which is a relatively clear criterion, the designer？s subjectivity involved in the design of concrete tunnel lining might be reduced.