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.