Unified model for internal force and deformation of shield segment joints and experimental analysis

First, based on a series of tests on reinforced concrete segment joints, the rotational moment-angle models for segment joints including linear, bilinear and nonlinear models and the axial force-deformation and shear force-deformation piecewise models are summarized and proposed, and the theoretical models are also given to describe the effect of the initial torque of bolts and axial force on joint stiffness. Second, based on the bending tests on flat plate segments and arch segments with or without sealing materials, the parameter determination methods for various stiffness models and the model selection principles are proposed, and the effect of the initial torque of bolts and axial force on joint stiffness is discussed. Based on the shear tests on flat plate segment joints with or without sealing materials, the parameter determination method for three-stage shear force resistance stiffness model is proposed. The results have proved the applicability of these joint stiffness models and will promote the application of beam-joint model theory in design practice.