Research On Seismic Failure Mechanism And Anti-seismic Performance Of Seat Abutment

With the continuous accumulation of people's understanding of bridge earthquake damage in recent years,the research on bridge seismic design theory and fortification measures is getting deeper and deeper.The abutment plays a vital role in the bridge structure system,that is,supporting the bridge superstructure and The embankment is connected.The previous earthquake damage investigations showed that there are generally varying degrees of damage to the abutment during the earthquake,but the current relevant research or related codes do not provide detailed guidance on the seismic design of the abutment.This paper studies the most widely used seated abutments,analyzes and considers the mechanical properties of the abutment model of the superstructure,backfill,pile foundation,and foundation soil under the action of earthquakes,and focuses on the exploration of the abutment structure and foundation parameters,The impact of the seismic performance of the abutment.The details are as follows:(1)The Baihua Bridge was taken as the engineering background,based on the ABAQUS platform,a refined model including the abutment,backfill,foundation soil and pile foundation was established,and the whole process of the abutment under horizontal load was analyzed.The destruction mechanism and influencing factors were compared with the actual earthquake damage to verify the effectiveness of the finite element simulation,which provided a model basis for the next study.(2)The finite element model was used to analyze the influence of the back wall thickness and reinforcement distribution on the seismic performance of the abutment.The results showed that the change in the thickness of the back wall has the most significant impact on the damage form of the abutment under earthquake.In general,the back wall would be destroyed before the pile foundation.When the thickness of the back wall was 50cm,the pile foundation and the abutment would crack simultaneously.The general shape of the backfill cracking surface was a semi-parabolic shape extending from the junction of the root of the back wall and the table cap to the back of the table.The extension range was generally 1.5 to 2.5 times of the back wall height.(3)The finite element model was used to analyze the influence of pile diameter and foundation soil type on the seismic performance of the abutment.The study found that the change in pile diameter has a greater impact on the bearing capacity of the abutment than the foundation soil type.The failure forms of the back wall were all inclined section failures,and the change of pile diameter had a greater impact on the disturbance area of the backfill than the type of foundation soil.