Research On Similar Design And Analysis Of Centrifuge Shaking Table Test For Deepwater Pier On Soft Soil Foundation

In recent years,in order to build a more complete transportation network,my country has successively built a number of deep-water bridges.As the lifeline of a national transportation hub,once a deep-water bridge is damaged by an earthquake,it will cause heavy economic losses and casualties.The destruction of bridge pier components is the main reason for the destruction of bridge structures.The bridge piers in deep water are often in soft soil geological conditions.At the same time,considering the dynamic water and the pile-soil interaction can truly reflect the dynamic characteristics of the bridge pier and the seismic response.Centrifuge shaking table model test is an important test method to study the dynamic characteristics and seismic response of bridge piers.The similar relationship between the test model and the physical quantities of the prototype is the basis of the model test design.Based on the centrifuge shaking table test of deep water bridge piers on soft soil foundation,this paper proposes a model similarity design method that considers soil-structure coordination and similarity.The scientificity of the similarity relationship directly affects the reliability and rationality of the prototype bridge pier structure response.It provides a certain reference basis for the model design and experimental research of the centrifuge shaking table test,and it is of great significance to the study of the dynamic characteristics of the pier under the action of the multi-medium body and the influence law of the seismic response.The main research contents of this paper are as follows:(1)For the centrifuge shaking table test of deep water bridge piers on soft soil foundation,for the pile-soil-pier structure system under horizontal dynamic load,based on the Bockinghamπ theorem,a dimensional analysis method is used to propose a model considering the similarity of soil-structure coordination The similarity design method obtains the similar relationship between the physical quantities of the prototype of the pile-soil-pier structure system and the test model.(2)Taking the actual engineering pile foundation pier structure as the prototype analysis object,using the soil-structure coordinated similar similar design method to carry out the test model design,using the centrifuge shaking table to carry out the dynamic characteristic test of the soft soil foundation pier model,and the bridge pier model is And the natural vibration frequency under different water depths.In response to the above tests,ABAQUS software was used to establish the experimental prototype and the finite element numerical model of the model respectively,and the modal analysis of the bridge pier prototype and model structure was carried out.Comparing the test results and the numerical simulation results to verify the correctness of the finite element numerical model;comparing the numerical simulation results of the pier prototype and the model structure dynamic characteristics,the results show that the errors of the two are small,and the mode shape and natural vibration The frequency can achieve a good similar effect.(3)Based on the numerical model verified above,a numerical simulation of the dynamic response of the pier prototype and model structure under earthquake action is carried out.The influence analysis of the model dynamic similarity relationship is carried out,and the dynamic response of the bridge pier prototype and the model structure under different ground motion intensities,different water depths,and different foundation soil elastic moduli are respectively compared and analyzed.The results show that the prototype and model structures under different ground motion intensities,water depths,and elastic modulus of foundation soils are in good agreement with the pier top acceleration,the relative displacement of the pier top and the pier bottom stress time history curve,the waveforms are consistent,and there is no peak leakage.There is also no peak misalignment,and the dynamic response amplitude error is small,and with the increase of the acceleration peak,the similarity error of the dynamic response amplitude of the bridge pier prototype and model structure increases.This verifies the accuracy and applicability of the proposed soil-structure coordinated similar design method.