Abstract: Investigating the dynamic response and damage condition of variable-section single pile in seismic subsidence site, taking Xiang’an Bridge as the engineering background, the dynamic response of variable-section single pile under 0.10g–0.45g ground vibration intensity was investigated through large shaking table tests, and the damage degree was evaluated and analyzed. Results are as follows: Influenced by the seismic subsidence characteristics of the soil layer, the top horizontal displacement, acceleration, and bending moment of the variable-section single pile tend to increase with the increase of vibration intensity, while the base frequency of the variable-section single pile gradually decreases. The maximum bending moment of the variable-section single pile occurs at the seismic subsidence soil stratum demarcation, where the ground shaking strength of 0.30g exceeds its flexural capacity. At a ground vibration intensity of 0.20g, the top horizontal displacement, acceleration, bending moment of the variable-section single pile increase significantly, and the base frequency of the pile decreases abruptly. Based on the system damage theory, the damage condition of variable-section single piles in seismic subsidence sites can be divided into three stages: stable stage, intensified damage stage, and plastic failure stage. At the end of the test, bending plastic damage occurred at the location of the variable section.

Key words: bridge engineering, seismic settlement for soft soil, shaking table test, variable-section single pile, dynamic response