饱和分层地基上列车运行引起的地面振动分析

Analysis of Ground Vibration Induced by Trains on Saturated Layered Ground

摘要:

基于薄层法原理，将圆柱坐标系下饱和土的Biot轴对称波动方程在竖向进行离散，沿切向坐标及轴向分别进行Fourier级数分解和Hankel变换，得到饱和层状介质中频域波数域中的位移基本解表达式，再利用Hankel逆变换和Fourier综合，求得频域柱坐标系下的位移表达式.结合运行列车轨道地基的振动模型，对饱和分层地基上列车运行引起的地面振动进行分析.详细讨论了渗透系数、孔隙率、流体黏滞系数和剪切波速等饱和土层参数对振动传播与衰减的影响规律.研究表明：地基的第1层土体参数对列车运行引起的地面振动的影响比第2层土体参数的影响显著，饱和土体的渗透系数、孔隙流体动力黏滞系数、孔隙率和剪切波速是影响地面振动的主要参数.

Abstract:

The thin layered method (TLM) is adopted to derive the solution of Lamb’s problem for layered saturated foundation under the action of dynamic loads. The displacement expression in the frequency wave number domain for layered saturated medium is obtained by discreting Biot’s axisymmetric dynamic equation in vertical coordinates, and by the Fourier series decomposition in tangential coordinates and Hankel transform in axial coordinates. Then the inversion of Hankel transform and Fourier synthesis are used to get the displacement expression in the frequency domain. Combined a moving train track ground interaction model, a parametric study is given to evaluate the ground vibration induced by train moving loads on the saturated layered ground. The effect of the soil parameters, such as permeability coefficient, porosity, fluid viscosity coefficient and shear wave velocity, on the attenuation of ground vibration is investigated and discussed in detail. The results show that the parameters of the first layer affect ground vibration induced by train more significantly than those of the second layer. It is also found that the permeability coefficient of soil, the fluid viscosity coefficient, porosity and shear wave velocity have great influence on the ground vibration.