Abstract: The new socket joint (CT joint) has been increasingly adopted in hydraulic tunnel engineering due to its superior waterproof performance and high construction efficiency.However, its failure mechanism under engineering loads is complex.This study established a multi-factor coupled numerical model incorporating the shield shell, segment, and CT joint to analyze the deformation and damage evolution of segments under multi-source and multi-dimensional external loads.The mechanical characteristics and failure modes of the CT joint are investigated, and corresponding engineering countermeasures were proposed.The results show that the head-down and tail-up posture deflection of shield shell can lead to the "upward bench" dislocation between adjacent segments, leading to higher stress and plastic strain on the lateral sides of adjacent joints compared to the upper and lower sides.Shield shell squeezing primarily causes plastic yielding in the CT joints on both sides of the segment due to dislocation shearing and co-directional bending, with yielding concentrated at the thin ribs of the T-shaped end.In addition, the shield shell squeezing mainly cause significant tensile damage to the segments that are currently or have just completely detached from the shield tail in the upper block.When the deflection angle is small, it mainly leads to local tensile crack, however when the deflection angle becomes large, it significantly increases the tensile and compressive damage on the lower parts of segments, and also makes the shear effect on the adjacent joints on the right side between 60°and 120°larger.Controlling the shield shell deflection angle below 0.8℃an prevent a significant reduction in the safety reserve of segments.This study provides valuable insights for the construction and design optimization of socket joints in water conveyance tunnels.