层状地基中瑞利波随深度的衰减特性

层状地基中瑞利波（Rayleigh wave）的传播规律以及随深度的衰减规律是工程环境微振动分析与控制研究的关键问题之一。采用解析法（矩阵传递法）分析了层状地基中瑞利波弥散曲线，并在此基础上研究了各种频率下不同类型土层（上软下硬、软夹层、硬夹层）中瑞利波位移随深度衰减规律，通过与弹性半空间解的对比发现，瑞利波位移随深度的衰减规律与频率、土层分布密切相关：频率越高，传播深度越浅；特殊土层（软夹层、硬夹层）的存在会局部显著地改变其衰减规律，并且位移峰值的分布受到频率和土层分布的共同影响。最后，将该方法用于分析上海光源工程地基条件下瑞利波随深度的衰减规律，并与现场深孔微振动测试数据进行了比较。结果证明，与弹性半空间解相比，层状地基中瑞利波随深度的衰减规律可以更为准确地反映真实条件下瑞利波随深度的衰减规律。

Attenuation characters of Rayleigh wave in layered soils

Attenuation characters of Rayleigh wave in layered soils are key factors for environmental micro-vibration control and analysis. Transfer-matrix is used to calculate dispersion curve of Rayleigh wave in layered soils. A thorough discussion is done on Rayleigh wave attenuation characters in different kinds of layered soils (upper-soft-and-lower-hard, middle-soft and middle-hard layered soil) under different vibration frequency; and some conclusions are drawn as follows: (1) Attenuation characters of Rayleigh wave in layered soils are influenced by vibration frequency and profile of layered soils; (2) Higher vibration frequency, faster attenuation; (3) The existence of special soils (soft soil or hard soil) can locally change the Rayleigh wave attenuation characters; (4) Location and amplitude of displacement is governed by vibration frequency and profile of layered soils. Finally, this approach is applied for calculating attenuation characters of SSRF site; and results have a good agreement with field test data. It is convinced that, comparing with attenuation curve in elastic half space, attenuation curve in layered soils can more reasonably simulate propagation of Rayleigh wave in layered soils.