Study on shear mechanical behavior of shield tunnel segment joint with fixing tenon
The hollow conical cylindrical fixing tenon, wrapped around the bolt of shield tunnel segments, effectively controls the displacement and value of shield segment misalignment, forming a "segment-fixing tenon-bent bolt" joint configuration with the segment and bolt. This study investi-gates the compressive conditions of shield tunnel segments, specifically the structural mechanics and failure mechanisms of the "segment-fixing tenon-bent bolt" joint under shear loads, focusing on a lon-gitudinal joint of shield tunnel lining connected by bent bolts with dimensions of 7.5 m inner diameter and 8.3 m outer diameter. Firstly, a three-dimensional finite element model is established to numerically simulate the entire shear failure process under axial forces of 196, 392, 588, and 784 kN. Subsequently, the shear failure process of the joint, mechanical characteristics of the fixing tenon and bolts, and the deformation and failure characteristics of the segment joint surface are analyzed. Finally, prototype shear failure tests validate and complement the numerical results. The study results reveal that the entire shear failure process of the "segment-fixing tenon-bent bolt" comprises four stages including static friction at the contact surface, elastic deformation and plastic dislocation of fixing tenon, and bolt shear failure. During the elastic deformation stage of the fixing tenon, the tenon exhibits a "flattened" shape. During the plastic dislocation phase of the tenon, the plastic yield zone first appears on the outer arch of the tenon. As shear load increases, plastic zone extends to encompass most of the tenon's end and cross-sectional areas, with excess shear loads transferred from the tenon to the bolt during plastic failure. Stress on the bolt rod body starts from the plastic dislocation stage of the fixing tenon, leading to "straightening" failure on the loaded side rod body and bending shear failure on the fixed side. The concrete on the joint surface of the shield tunnel segment exhibits a plastic zone in the later stages of the fixing tenon's plastic deformation phase, initially located on both horizontal sides within the tenon slot. As shear forces increase, the plastic zone expands outward, eventually connecting with the plastic zone in the curved hand hole inside the segment, forming a "hand hole-bolt hole-hand hole" plastic failure zone.
shield tunnelfixing tenonsegment jointmechanical behaviornumerical simulationprototype test
万方数据
维普
