Abstract：

The ventilation pipeline above the underground railway travel area is affected by the dynamic cyclic impact of the piston wind and its own vibration in underground railway train for a long time, which is prone to the accidents of the hanger loosing and the wind pipe falling off, which poses a serious threat to the safety of the train. Therefore, it is very important to accurately grasp the dynamic load performance and safety reliability of the hanger. Designs and manufactures the air duct hanger and the special loading device, and carries out cyclic dynamic loading fatigue tests and limit drawing tests with a frequency of 5 Hz and a total of 2 million times. The results show that the structural form of the hanger and the type of connecting bolt directly affect the dynamic load performance and safety reliability. When channel steel is connected with surrounding rock, the dynamic elastic deformation and recovery process of channel steel are obvious. The bottom cutting bolt is far stronger than the ordinary expansion bolt. The common expansion bolt fails before the hanger, and the hanger fails before the bottom cutting bolt. The welding strength of round steel and angle steel is higher than that of bolt thread connection. The optimal structure type of the hanger is “A-type hanger plus bottom cutting bolt”, and the pre-tightening force of the bolt during installation should be controlled from 40 Nm to 43 Nm.