MATERIAL AND MECHANICAL CHARACTERISTICS OF THE FRP-KEY JOINT FOR SHIELD TUNNEL SEGMENTS

The authors developed a new type joint of shield tunnel segment suitable for highly stable ground. Called “FRP-Key” the new joints consist of FRP tongues partially embedded in the surface of the circumferential joint and the longitudinal joint, and they are fitted with the groove cut on the opposite surfaces. The FRP-Key joint ensures transmission of shear forces and controls the positioning of segments during assembly. This reduces the time required for segment assembly in situ and saves the manufacuturing cost of concrete forms as the joint can be preinstalled in steel formwork. This paper presents the characteristics of FRP and the mechanical characteristics of the FRP-Key joint obtained from various tests, and describes the method of designing segments with FRP-Key joint.