非均质堤坝振动特性简化分析

A Simplified Approach to Evaluation of Vibration Characteristics of Non-Homogeneous Embankments

将坝体视为一维弹性剪切振动体系，考虑堤坝土料特性沿坝高的非均匀分布及坝体宽度沿高度的变比，推导出堤坝横向剪切振动时频率、振型函数、振型参与系数等的封闭型解析表达式及地震反应估算公式，基于参数分析探讨了各种因素对坝体振动特性的影响，为非均质堤坝地震反应简化分析提供了基础。

A general non-homogeneous shear beam model is developed to account for any possible situation such as variat ions of soil density and shear modulus with depth and irregular cross-section of embankments. Closed-form analytical expressions are derived for natural frequencies, modal displacements, participation factors and others for all cases. In this approach, the average shear modulus across the width of embankments is expressed as a sectional power function of depth. Numerical results are presented in a graphical form through a set of non-dimensional parameters. The effects of several factors associated with non- homogeneities both in material properties and in geometric shape on vibration characteristics of layered embankments are discussed. Some conclusions drawn here may be of pratical significance.