Mechanical Performance of Steel Fiber Reinforced Concrete Segment with Oblique Bolt Joints
This study explores the applicability of oblique bolt joints in small-diameter shield tunnel beam melting(TBM)tunnels,clarifying their mechanical properties and damage mechanisms.A segment structure with an external diameter of 6.2 m and a thickness of 350 mm was utilized as a prototype for conducting bending performance tests on steel fiber concrete segments with oblique bolted joints under four different horizontal axial force conditions.The analysis focused on the deformation characteristics and flexural performance of the segment joints across varying axial force levels,as well as the failure processes and mechanical properties under failure conditions.The results showed that the higher the axial force on the segment joints,the higher the joint stiffness,requiring larger bending moments to open the joint.In other words,the joint axial force can be actively increased by increasing the bolt preload or by applying annular prestressing to improve the joint stiffness.Compression of the sealing gasket under joint axial force results in stress concentrations within the sealing groove.Therefore,selecting an appropriate sealing gasket or optimizing the sealing groove structure is essential in the design process.The study also found that enhancing the compressive strength of the top concrete and reducing the insertion angle of the oblique bolt significantly improve joint bearing capacity.These findings provide valuable guidance for the design of segment joints.