Study On Multiple Scattering Of Plane P Waves In An Arbitrary Arrangement Of Piles In Saturated Soil

With China’s rapid economic development,city rail transit construction demand is increasing.Especially in recent years,with the construct and use of subway,high-speed rail and other rail transportation,the environment vibration pollution problems are increasingly prominent.Using the vibration isolation barrier is an effective measure to control the environmental vibration pollution.The discontinuous barrier,such as the pile-rows,has achieved good shielding effect in practical engineering.The previous research on scattering problems of elastic waves by pile-rows based on the assumption of single scattering,which are ignored the effects of multiple scattering induced by coherent scattering phenomena of elastic wave in the barrier.On the other hand,the soil medium is assumed as single-phase elastic medium,which is clearly not consistent with saturated soft soil,so that it is necessary to consider the dynamic response of fluid in saturated soil.This dissertation is theoretically solved the multiple scattering problem of arbitrarily arranged rows of piles in saturated soil under P waves incident theoretically.Numerical examples are carried out to,analyzes the influence factors of vibration isolation effect;in order to get saturated soil piles barrier theory system,which provides the design basis for engineering application.The main work of this dissertation are as follows:1.Based on the saturated soil theory of Biot,the multiple scattering theory of acoustics and electromagnetics,and the wave function expansion method,an analytical model for the scattering of P waves by arbitrarily arranged and arbitrary radius cylindrical scatterers is established.According to the boundary conditions of the pile and soil,the scattering coefficient is obtained.2.The scattering wave field of P wave in saturated soil is solved when the scatterer are cylindrical cavities.According to the stress and displacement boundary conditions of the cavity and soil,the scattering coefficients are obtained.Through the concrete example analysis,it is depicted the contour map of dimensionless displacement varying with the spacing of cavities,three dimensional mesh of dimensionless displacement varying with pile spacing,curves of dimensionless displacement varying with the number of piles,and the contour map with different dimensionless displacement arrangement in saturated soil.The effect of barrier isolation is analyzed with the change of dimensionless displacement.3.The scattering wave field of P wave in saturated soil is solved when the scatterers are elastic piles.According to the elastic pile,soil stress and displacement conditions,scattering coefficients are obtained,It is used specific examples to analyze the effect of vibration isolation with main parameters such as row spacing,pile spacing,pile soil shear modulus and pile numbers ect.4.Based on the Grafs addition theorem,the rest of the scatterers scattering coordinates are transformed to the target scattering body coordinate systems,It is obtained multiple scattering theory formula of pile barrier for the P waves incident in saturated soil and the complex coefficients of multiple scattering are achieved as well,Numerical example are also related to presented.In this dissertation,the effect of different parameters related to the vibration isolation effect is studied,such as scattering orders,row spacing,pile spacing,pile numbers and arrangement form.