Long-term operation state monitoring and stress-deformation mechanism research of bridge abutment anchorage structure

The Pi-type terminal spine anchorage structure is an important part to limit the longitudinal slab track structure displacement in the subgrade-bridge transition section. This paper analysed the deformation laws of the anchorage structure through three consecutive years field monitoring data. Experimental results showed that the temperature gradient of track structure was larger in shallow layer than in deep layer, and both were larger in summer than in winter. The gap of the wide-narrow joint and the gap between the HGT layer and the transition plate changed inversely with the air temperature. The gap was more than 8 mm in January, but it was nearly 0 mm from June to September. The subgrade fillers in the anchorage area moved to the subgrade section in summer and to the bridge section in winter, and the displacement was larger in shallow layer than in deep layer. In addition, the stress-deformation characteristics and the damage mechanism of the anchorage structure were analysed by a refined numerical model. Numerical results showed that the junction between the vertical wall of the major terminal spine and the transition plate was the most sensitive part. From the major terminal spine to the small terminal spine area, the temperature stress and longitudinal displacement of the terminal spine and the surrounding subgrade gradually decreased. The deformation of the anchorage structure will affect the service status of the track structure at the junction. The terminal spine cavity may cause the over displacement and damage of the anchorage structure.