Experimental investigation of the nonlinear behavior of segmental joints in a water-conveyance tunnel

The segmental joint of a shield tunnel lining is one of the most critical components to consider when designing the lining. In this study, the mechanical behavior of two types of segmental joints used in a water-conveyance tunnel was investigated through a series of full-scale laboratory tests. Experimental data show that joint behavior is greatly influenced by the details of joint section, loading conditions, and the contact conditions between the two adjacent segments of the joint. To understand the mechanism of the behavior observed in the experiments, a finite element model that explicitly models bolts, cast iron panels, and the initial contact condition was developed. The numerical results of the FE model matched well with the experimental data, and the effect of the contact between segments on the joint stiffness was quantified. Results show that even a small initial gap (e.g. 2 mm) between segments has a significant effect on the joint stiffness. These findings can provide important guidance on the design of concrete segmental linings for future water-conveyance tunnels.