The engineering practice of frame drainage well in tailings pond show that the caulking state between the column of drainage well and the end of arch plate will significantly affect the overall safety level of the structure.Taking the drainage well under the typical accident case as an example, based on the in-depth analysis of the end joint filling quality, three stress models of double hinged arch, simply supported beam and spring arch are constructed respectively to simulate several different contact states between the column and the end of the arch plate.By analyzing the internal force evolution law and structural bearing capacity of arch slab under different models, the key factors affecting the safety of arch slab structure are explored.The analysis results show that the end joint filling quality is good, the actual stress mode of the arch plate is the spring arch model with high end stiffness coefficient, which is close to the theoretical double hinged arch model.At this time, the bending moment of the arch plate is low, the axial force is large, and the reliability of the arch plate structure is high.When the quality of end joint filling is poor, the stress mode of arch plate will be transformed into spring arch model with low stiffness or even simply supported beam model.At this time, the bending moment and shear force of the arch plate increase, the axial force decreases, and the structural reliability decreases greatly.In order to improve the structural safety, the arch plate should be designed according to the spring arch model with very low stiffness or simply supported beam model.During daily operation, while prefabricating the arch plate in strict accordance with the design, strengthen the management of the whole process of plugging and installation, and ensure the quality of mortar joint filling at the end.