FUNDAMENTAL RESEARCH ON THE FALLING OF CONCRETE PIECE FROM TUNNEL LINING

Abstract

This paper describes the method which quantitatively evaluates the falling of concrete pieces from tunnel linings, comparing the shear stress acting on crack surfaces with the shear capacity. The shear capacity under the various width, inclination angle, and roughness of cracks is investigated based on a double shear test simulating the falling of concrete pieces and on a simulation method, whose applicability is also described in this paper. Core samples including the crack surfaces are obtained at actual tunnels and crack surfaces roughness and its distribution are grasped. The safety in the falling of concrete pieces is estimated based on the proposed method under the situation assumed at the actual tunnels.