Study on Shear Mechanical Performances of Circumferential Mortise and Tenon Joints with Oblique Bolts in Shield Tunnelling
To investigate the shear mechanical performances and shear failure mechanisms of circumferential mor-tise and tenon joints with oblique bolts in super-large diameter shield tunnels,a study was conducted based on the Haizhu Bay Tunnel project in Guangzhou.A three-dimensional refined numerical model of circumferential segment joints was developed using a concrete plastic damage constitutive model.The deformation behavior,bolt stress,mor-tise and tenon reinforcement stress,and structural damage of the circumferential joints were analyzed under varying shear states and longitudinal forces.The results indicate that:The deformation of circumferential segment joints ex-hibits distinct phases under both forward and reverse shear conditions,comprising four stages.The shear stiffness of circumferential joints under forward shear state is higher than that under reverse shear state;The effect of longitudi-nal force on enhancing the shear stiffness of the circumferential segment joints is primarily observed in the first de-formation stage;Under forward shear state,bolt deformation is dominated by tension,whereas under reverse shear state,shear deformation prevails.Bolts quickly reach yielding once in contact with the bolt holes,especially under reverse shear condition,where the contribution of bolts to shear stiffness is limited;Mortise and tenon reinforcement improves structural ductility and prevents brittle failure;Concrete damage at the contact points of bolt holes and mortise and tenon joints is characterized by compressive crushing.Compared to bolts,mortise and tenon features significantly enhance the shear stiffness and bearing capacity of the circumferential segment joints.
万方数据
维普
