Numerical analysis of tunnel segments strengthened by steel–concrete composites

Abstract

In order to study the feasibility of strengthening of segmental tunnel linings by using steel–concrete composites (SCC), a three-dimensional (3D) finite element (FE) model is proposed in this paper. The nonlinear mechanical behavior of concrete is described by a plastic-damage model. The nonlinearity, resulting from the interface of the SCC and reinforced concrete (RC) segments, is simulated with the help of a system of springs. The analysis results are compared with those obtained from a full-scale test of a tunnel segment. Their agreement validates the usefulness of the 3D FE model. Numerical re-analysis of the test shows that the interfacial connectors govern both the strengthening effect of SCC and the failure pattern of the strengthened segments. Thus, the force-transmitting capacity of the interfacial connectors should be concerned in design activities. As regards the circular segments, the interfacial connectors refer to both the shearing and the stripping connectors. The composite effect of the SCC and RC segments increases with the increasing number of these connectors. The latter, therefore, results in the increases of the bearing capacities and stiffnesses of the strengthened segments. Those increases become insignificant as the number of these connectors is sufficient to ensure a perfect composite effect of the SCC and RC segments. In addition, the numerical simulations show that using high-performance steel shell (HPS) or/and ultra-high-performance concrete (UHPC) is an effective way to increase the strengthening effect of SCCs.

Keywords

• Nonlinear analysis
• Concrete structures
• Composite structures
• Shield tunnels
• Full-scale test