Mechanical Performance of RC and SFRC Precast Tunnel Lining Segments: A Case Study

Abstract

Tunnels play a key role in facilitating the movement of people, goods, and services. The functionality of tunnels depends on the structural and durability performance of its lining system. Tunnel lining systems act as lines of defense against large overburden loads and complex geotechnical surrounding conditions. In this study, the structural behavior of precast concrete tunnel lining (PCTL) segments from a subway extension tunnel project in Canada was investigated. Flexural monotonic and cyclic load tests were performed on full-scale conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) PCTL segments to evaluate their bending resistance. Moreover, a thrust load test was conducted to simulate the thrust loading action during tunnel boring machine operation. As expected, flexural test results indicate that the peak load-carrying capacity of RC segments was higher than that of the SFRC segments. However, SFRC segments exhibited higher cracking load and more stable post-peak cracking behavior compared to that of RC segments. RC and SFRC segments exhibited similar behavior during thrust load tests. Both types of segments satisfied the design flexural capacity and thrust loading criteria for monotonic and cyclic loads. The SFRC crack control capability supports its potential as an alternative for conventional RC tunneling segments.