极限失效下管片接头抗弯性能及耦合影响量化OA

During shield tunnel operation,segment joints are susceptible to deterioration and failure due to long-term service loading and disturbances from surrounding construction activities.Horizontal axial force and jacking force are key factors affecting the bending stiffness of longitudinal joints in shield tunnels.Therefore,this study conducted full-scale flexural tests on longitudinal joints considering jacking force under extreme conditions where circumferential constraints adjacent to segment longitudinal joints fail.The finite element model was calibrated against experimental results,and the influence patterns of horizontal axial force and jacking force on parameters in the nonlinear flexural stiffness expression of longitudinal joints were quantitatively analyzed.This paper enhances the flexural performance evaluation of longitudinal joints.The research shows that the division of flexural stages based on the moment-rotation relationship of longitudinal joints is consistent with the variation pattern of cumulative structural response values in bolts.The flexural process of longitudinal joints with oblique bolt connections sequentially experiences six stages:elastic,crack initiation,plastic development,stiffness recovery,yield propagation,and failure,validating the reliability of using cumulative structural response values for flexural stage classification.The flexural performance of longitudinal joints increases rapidly with increasing horizontal axial force,while the enhancement effect of jacking force is significant under low horizontal axial force scenarios.In the moment-rotation fitting relationship,the initial stiffness factor b increases with increasing jacking force but shows a negative correlation with horizontal axial force,which stems from the dual effects of horizontal axial force:increasing ultimate bearing capacity while generating negative bending moment that causes"auxiliary joint opening"effects.