Static And Dynamic Analysis Of Bridge Pile Foundation In Liquefactable Site

The results of earthquake damage investigation show that large ground deformation caused by liquefaction of liquefiable ground under earthquake is the main cause of pile foundation damage.Considering that liquefiable sites are often liquefied in a short time under strong earthquakes,and pile body is destroyed under the combined action of soil lateral displacement and ground vibration.Therefore,this paper takes the regulation of distribution of internal force of bridge pile foundation in liquefiable site under strong earthquake as the research object,and takes the distribution of internal force of bridge pile foundation in liquefiable site as the research object.The stress of pile-soil system under lateral displacement and ground vibration loads is investigated respectively,then and the similarities and differences of internal force distribution are compared,and suggestions for pile body design are put forward.The contents and methods are as follows:Firstly,the lateral displacement of the loaded soil structure is simulated.On the basis of the above prototype model,four factors are simulated,namely,the thickness of overlying layer,the thickness of liquefied layer,the amount of soil lateral displacement and the load on the top of pile.Secondly,the force of pile body in the above three soil models is taken as the research object to carry out dynamic simulation.Six seismic waves of different intensities were loaded to obtain the envelope diagram of the internal force was drawn.By comparing the internal force distribution of piles under the above two loading conditions,the internal force distribution law is obtained.Finally,The reinforcement measures are applied to the pile body in the above dynamic loading model.By comparing the effect of hoop reinforcement and the simulated internal force,the protection degree of hoop reinforcement to the pile body under earthquake input is evaluated.The conclusions are as follows:(1)Thickness of liquefied layer,lateral displacement of soil and thickness of overlying non-liquefied layer all have significant effects on the stress of pile foundation.Vertical load on the top of the pile has no significant effect on the internal force of the pile,but it will affect the settlement of the pile,which needs further exploration.(2)The maximum values of axial force,shear force and bending moment of piles increase with the increase of seismic intensity.In contrast,the distribution of internal force of pile under seismic input is quite different from that under lateral displacement input.Especially the location of the maximum is very different.(4)The hoop protects the pile foundation well and reduces the force on the pile body greatly.In addition,the stress distribution of pile body does not change obviously with the application of hoop.