Numerical modeling and parametric study of hybrid fiber-rebar reinforced concrete tunnel linings

Fiber-reinforced concrete (FRC) not only has the function of controlling cracks but also shows considerable strength. It has been widely used in shield tunnels in recent years. Current numerical models of FRC tunnel linings mostly focused on the component level behavior instead of the structure level. An experimentally validated numerical model for hybrid fiber-rebar reinforced concrete tunnel linings is developed in this study to evaluate the nonlinear characteristics of FRC linings, including nonlinear joint behavior and material nonlinearity. The proposed model accurately captures the overall behavior of an FRC tunnel lining while achieves the efficiency of calculation, and can be used to improve the current design. After the model is validated with full-scale experimental results, a numerical procedure is proposed to obtain the maximum rebar replacement ratio of FRC tunnel linings using the validated numerical model. This procedure follows a two-step comparison of the structural performance between the FRC and traditional reinforced concrete (RC) lining structures to ensure the FRC tunnel linings can achieve comparable performance with a reduced amount of traditional steel bar reinforcement. Moreover, the effects of fiber types and dosages on the behavior of FRC linings are also investigated.