Numerical Simulation Analysis And Research On The Influence Of Underground Diaphragm Wall On Pile Foundation Under Earthquake Action

Earthquakes occur frequently across the vast territory of our country,and frequent earthquakes have caused a lot of damage to buildings,resulting in a large number of casualties and serious economic losses.Therefore,it is necessary to carry out seismic design of buildings.Pile foundation is one of the most commonly used foundation forms.Because of its low cost and high bearing capacity,it is widely used in high-rise buildings,underground structures,foundation pit engineering and other fields.It plays a vital role in building safety,so its seismic resistance Performance to the safety of the building cannot be ignored either.With the need of social and economic development,there are more and more complex structures such as super high-rise buildings,deep and large foundation pits,and the support forms are more diversified.As a common form of foundation pit support,underground diaphragm walls are also commonly used in high-rise buildings.Supporting projects of basement exterior walls and complex foundation pits.At present,there is little research on whether the supporting structure can effectively reduce the impact of earthquake on the building.Research on the seismic performance of the diaphragm wall on the pile foundation is very important to ensure the safety and economy of the project.Therefore,it is necessary to analyze the impact of the diaphragm wall on the pile foundation under the action of an earthquake.This paper uses ABAQUS software to establish a three-dimensional finite element numerical model to study the influence of the diaphragm wall on the pile foundation under the action of earthquake.It is mainly simulated by changing the depth of the diaphragm wall,the distance between the diaphragm wall and the pile foundation,and the buried depth of the pile foundation.The pile body bending moment,shear force,axial force,horizontal displacement and superstructure of the pile foundation are simulated.Acceleration and displacement are analyzed for dynamic response.The main conclusions obtained in this paper are as follows:(1)The time-history analysis of the internal force of the pile top under the action of an earthquake shows that the peak internal force of the pile top when there is an underground continuous wall is less than the peak value of the internal force at the top of the pile without the underground continuous wall.The time history value of the pile top internal force changes with the depth of the diaphragm wall,the distance between the diaphragm wall and the pile foundation,and the buried depth of the pile foundation.(2)Under the action of the earthquake,the underground diaphragm wall effectively reduces the value of the internal force of the pile and the value of the horizontal displacement of the pile.The maximum value of pile internal force and the maximum value of horizontal displacement of pile 1(corner pile)decrease with the increase of the depth of the diaphragm wall.The internal force value and horizontal displacement value of pile 4(middle pile)are both small,and there is no obvious law.(3)Under the action of an earthquake,when the distance between the diaphragm wall and the pile foundation changes,the maximum internal force of the pile does not necessarily appear at the top of the pile,and the maximum value of the bending moment and the maximum shear force of the pile appear at the top of the pile.,The maximum axial force of the pile body appears at the top of the pile.The maximum value of pile internal force and the maximum value of pile horizontal displacement of pile 1(corner pile)increase as the distance between the underground diaphragm wall and the pile foundation increases.The internal force value and horizontal displacement value of pile 4(middle pile)are both small,and there is no obvious law.(4)Under the action of an earthquake,the analysis of the pile depth at different times shows that the maximum internal force of the pile does not necessarily appear at the top of the pile when there is an underground diaphragm,and the maximum horizontal displacement of the pile appears at the bottom of the pile.The maximum value of pile internal force of pile 1(corner pile)and pile 3(side pile)increases with the increase of pile depth,and the maximum value of pile horizontal displacement decreases with the increase of pile depth.The internal force value and horizontal displacement value of pile 4(middle pile)are both small,and there is no obvious change rule.(5)The time history analysis of the upper structure shows that when the depth of the underground diaphragm wall changes,the peak acceleration time with the diaphragm wall is greater than the acceleration time history peak without the diaphragm wall.The peak acceleration of the superstructure increases with the increase of the depth of the diaphragm wall;the peak displacement time history with the diaphragm wall is smaller than that without the diaphragm wall,and decreases with the increase of the depth of the diaphragm wall.(6)The time history analysis of the superstructure shows that when the distance between the diaphragm wall and the pile foundation changes,the peak value of the acceleration time history of the superstructure decreases as the distance between the diaphragm wall and the pile foundation increases.The impact on the peak of the displacement time history is small.(7)The time history analysis of the superstructure shows that when the buried depth of the underground diaphragm wall to the pile foundation changes,the peak value of acceleration and the displacement time history of the superstructure increase with the increase of the buried depth of the pile foundation.