Mechanical Properties of Segment Joints in Subway Shield Tunnels by a Full-Scale Test

This paper focuses on the mechanical properties of segment joints in subway shield tunnels. Firstly, a full-scale test is conducted to obtain the whole damage process and bending mechanical properties of a segment joint. The bearing process of the joint can be divided into four typical mechanical stages: concrete elastic stage, inner arc cracking stage, joint overall damage stage, and joint limit damage stage. The critical loads of the adjacent mechanical stage are defined as the joint characteristic loads. Secondly, a series of three-dimensional numerical models is performed corresponding to the full-scale test considering the concrete properties of elastic–plastic damage ontology. The reasonableness of the numerical simulation is verified by comparing the test and numerical simulation results. Finally, the mechanical properties of the segment joints are analyzed parametrically using numerical simulations in terms of material properties and external loads. Through variable reference analysis, it can be obtained that the actual construction of concrete with C60 grade and bolts with 8.8 grade can give the best effect of economic efficiency and improve the performance of joints, and axial force and bolt pre-stress can offset external loads and improve joint stiffness.