Study On The Influence Of Soil Stiffness Loss On Vibration Caused By Pile Foundation Disturbance Of Elevated Line

In recent years,with the gradual expansion of the scope of urban rail transit in China,more and more cities and people living in them enjoy the convenience brought by urban rail transit,but at the same time,the environmental vibration caused by urban rail transit in the process of operation is also increasingly prominent.Scholars have carried out a lot of research on this problem,and established a variety of environmental vibration models.However,in the current study of environmental vibration,the impact of subway construction is often ignored.With the development of geotechnical research,the construction process of tunnel and pile foundation has been proved to have a great impact on the surrounding soil,which also changes some soil parameters and charact eristics.In the calculation of environmental vibration,soil parameters are very important.At present,the research on environmental vibration has not considered this influence factor.In view of the lack of existing research,this paper explores the disturbance effect of pile foundation construction on the surrounding soil mass,and the accompanying loss of soil stiffness around the pile,and finally studies the relevant impact of the loss of soil stiffness around the pile on the environmental vibration.In this paper,the shear strain of the soil around the pile during the construction of pile foundation and the corresponding change of the stiffness of the soil around the pile are obtained through the simulation calculation.On this basis,the stiffness of the pile foundation soil model is modified,and then the corresponding environmental vibration calculation is carried out.Finally,the influence of soil disturbance caused by pile foundation constru ction on environmental vibration is analyzed.The main work of this paper is as follows:1.This paper summarized the research status and common research methods of environmental vibration.2.Using COMSOL multiphysics software to establish pile foundation soil model,simulated the construction process of bored pile,got the shear stress variable of soil around the pile under different disturbance degree,and then calculated the change a mount of soil stiffness around the pile combined with small strain model of hardened soil.3.Using um and ANSYS software,the joint simulation calculation were carried out,and the reaction force of bridge support under the operation speed of 80km/h of Metro A-type vehicle was calculated.4.According to the simulation results,firstly,the stiffness of the pile foundation soil model was modified,then the environmental vibration is calculated with the reaction force of the bridge support as the excitation,and the calculation results under various working conditions are compared and analyzed.Finally,the influence of soil disturbance caused by the pile foundation construction process on the environmental vibration was analyzed.