Centrifuge Test And Numerical Study On The Seismic Behavior Of Batter Pile Foundation In Lateral Spreading Soil

The liquefaction-induced lateral spreading is one of the most important reasons for the damage of a large number of bridges.And the seismic damage situation is particularly serious in the lateral spreading site with shallow non-liquefied soil layer.The seismic response of pile foundations on liquefaction sites is a sophisticated problem with numerous influencing factors.In recent years,this issue has attracted the attention of scholars at home and abroad,and related research work has also been increasing.However,China’s norm still lacks detailed descriptions and regulations for this part of the problem.The batter pile foundation is a commonly used engineering method to resist lateral deformation and destruction.However,the problem of the anti-seismic performance of the batter pile has still been debated.This paper firstly analyzed the case of the sloped pile foundation of Landing Road Bridge in the 1987 New Zealand earthquake by the method of layer reaction acceleration.The results of comparative analysis with the investigation show that the reaction acceleration method has great accuracy in simulating the resistance reaction of the foundation structure as well as the displacemen and tilt of the foundation,but there is a large error in the deformation simulation of foundation soil.Meanwhile,based on the case stady,sensitivity analysis of the strength reduction parameters and stiffness reduction parameters due to the soil liquefied was finished,and it is found that the simulation results are more sensitive to the stiffness reduction factors.Secondly,a centrifuge test was conducted on the batter pile foundation with soil layers inclined,and the influence of the shallow non-liquefied soil layer on pile foundation against the lateral spreading liquefied soil layer was considered and compared with the existing experimental results.The results show that the impact of shallow non-liquefied soil layers on the pile foundation is not only reflected in its direct interaction with the pile foundation,but also in the impact on the soil vibration response of the system.Shall ow non-liquefied soil layer affects the seismic response of the lower soil layer,including the degree of sand liquefaction,soil layer reaction acceleration and liquefaction depth,which finally change the internal force and deformation response of the pi le foundation.Finally,the accuracy of the reaction acceleration method in the analysis of the seismic behavior of the pile foundation against lateral spreading was further verified through the simulation of the centrifuge test.The reaction acceleration method can accurately simulate the internal force response characteristics of the pile foundation to a relatively high degree,if the influence of soil liquefaction is rationally considered and strength and stiffness reduction of the liquefied soil layer is reasonably dealt with.And the pile-soil interaction characteristics were analyzed through the pile-soil relative displacement,as the relative displacement of pile-soil to a certain extent relflects the distribution of the lateral thrust and lateral suppot to the pile foundation by the lateral spreading soil layer.The factors affecting the seismic response of the pile foundation on the lateral spreading site were also preliminarily explored.