Experimental study on settlement and punching behavior of full-scale RC and SFRC precast tunnel lining segments

Abstract

The overall stability of a segmental tunnel lining ring is highly dependent on the structural integrity of its individual precast segments, which provide protection against the surrounding exposure conditions. In this study, the settlement and punching behavior of full-scale conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) precast tunnel lining segments fabricated for a subway tunnel in Canada were investigated. Precast concrete tunnel lining (PCTL) segment specimens were subjected to mid-span load on their intrados faces. Such loading can be induced as a result of vehicular accidents inside the tunnel and/or soil settlement underneath the PCTL segments. Moreover, a punching test was conducted to replicate the expansion of rocks or other geotechnical surrounding conditions above or underneath the tunnel segments. The experimental results showed that the peak load carrying capacity of the RC segments was higher than that of the SFRC segments for both the settlement and punching behavior. However, SFRC segments exhibited higher initial cracking load, more stable post-peak cracking pattern compared to that of the RC segments and significant reduction in crack width. This makes SFRC attractive for the fabrication of segmental tunnel linings where the initial cracking is a governing criterion. Furthermore, it was confirmed that both the tested RC and SFRC PCTL segments satisfied common settlement and punching loads design criteria.