Pile-Soil-Structure Dynamic Interaction Analysis Subjected To High-Speed And Heavy Loads

Due to the high standard line requirements of high-speed railway,bridge is the main part of engineering construction.Moreover,the speed of high-speed trains is much higher than that of ordinary trains,which result in a higher dynamic response of high-speed railway bridges than ordinary railway bridges.In many cases,it is inevitable to adopt the form of bridges with large spans and high piers,in the case of soft foundation,pile-soil interaction caused by train vibration will affect the dynamic behavior of the structure.At present,researches on high-speed railways are far from mature.Therefore,more studies should be conducted on high-speed railway bridges.In previous studies,there was a simple study of the soil-pile dynamic interaction of foundation soil.Some of these studies to establish the analysis model of entire foundation soil,or the pile-soil interaction is equivalent to a continuously distributed spring-damper element.The contribution of the foundation soil is equivalent to the elastic resistance added to the bottom of the pier for consideration.In the study of the superstructure,the train can be equivalent to a multi-body model,and the train and track coupling dynamic equation can be established.These studies reveal the essential characteristics of the vehicle-bridge coupled dynamic behavior from the principle mechanical principle.However,these studies are too complex and lack practicability,so it is difficult to apply to practical projects.Therefore,it is important to consider the train vibration load reasonably and simplify the pile-soil interaction analysis model to make it more effective to consider the effect of pile-soil interaction on high-speed railway bridges in practical projects.The main research contents of this paper include:(1)A simplified expression of high-speed train vibration load is given by summarizing the previous researches.In this paper,the vibration load of trains based on track irregularity is used for the next step analysis.At the same time,several stepwise integration methods for solving differential equations with time-varying coefficients under moving loads are introduced.(2)Based on dynamic Winkler foundation beam model,the dynamic equilibrium differential equation was established without considering the axial force,the Laplace transform and transfer matrix method is used to obtain the transverse dynamic impedance under the dynamic load and verifying its frequency dependence through the calculation results of group pile model,and the horizontal dynamic impedance under the vibration load of multiple load components was deduced.(3)According to the research content,the appropriate element was selected in ANSYS software.A full-bridge finite model of 86m×142m×86m high-speed railway bridge with three spans was established.Analyze the dynamic response of the two models consider or not consider pile-soil interaction when the high-speed train passes,and verify the rationality of this model by comparing with the relevant test results.(4)The influence of parameters such as train running speed,pier height,compressive modulus of soil layer,pile length and track irregularity on the dynamic response of the bridge is analyzed.The calculation results show that parameter change will have an impact on the dynamic response of the bridge.It provides the basis for considering the influence of pile-soil interaction at the design stage for high-speed railway bridges.