Study On The Dynamic Response Of Friction-type Pile Foundation Under The Action Of Train Low-frequency Vibration

Pile foundation is an important infrastructure type of Deep foundation. In the currentera of rapid development of high speed railway, pile foundation is widely applied in theconstruction of high speed railway. Nevertheless, there is less research on pile foundationdynamic analysis under the action of low-frequency vibration. Train low-frequencyvibration is a top-down long-term repeated dynamic load, spreading from superstructure tothe foundation and meanwhile causing vibration. The characteristic of train load depends onthe degree of road unevenness, vehicle density, vehicle load and the speed. And also its loadamplitude and frequency frequently vary. Therefore, the study of foundation pile’s dynamicresponse under traffic loads is of great significance for confirming safe economic designparameters and further understanding the dynamic characteristics of bridge foundation inthe fast traffic loads.On the background of friction-type pile foundation subsidence project of high speedrailway, dynamic response of friction-type pile foundation under the action oflow-frequency vibration is studied in this paper by the means of numerical simulationanalysis. ANSYS finite element software is used in this thesis to build a three-dimensionalfinite element model in order to analyze the vertical static load and dynamic loads underpile-soil interaction law. The main research results are as follows:1、Under the action of low-frequency vibration, vertical dynamic response along thepile depth direction presents non-linear decrease. Then the effects of train loads on pilebottom are very small, and vertical stress is mainly distributed in three-fourths long range.The dynamic responses along the horizontal direction to soil decay rapidly, concentratingwithin3M to the pile center distance.2、Within the scope of imposed load and frequency, dynamic stiffness of pile-soilsystem increased with increasing load frequency. And frequency increases have good effecton dynamic bearing capacity of pile-soil, leading to the increase of its capacity. As the loadamplitude increases, the dynamic response of pile top does. Under the action oflow-frequency vibration, stress characteristics of piles are also influenced by pile groupeffect. 3、While pile groups under the action of low-frequency vibration for single pilelocations differ, the size and distribution of vertical dynamic response along the pile lengthdepth vary. Load distribution under the action of low-frequency vibration is not exactlysame with that under static load. Therefore, in the design of a pile group subjected todynamic load, train dynamic load distribution should be taken into consideration whencalculating pile structure.