层状半无限体浅部洞穴对表面响应谱扰动  

Disturbances in surface response spectra caused by shallow cavities in layered half spaces

作　　者：柴华友 柯文汇 朱红西 柴扬斐 王贤达 CHAI Hua-you;KE Wen-hui;ZHU Hong-xi;CHAI Yang-fei;WANG Xian-da(School of Civil Engineering and Architecture,Wuhan Institute of Technology,Wuhan,Hubei 430073,China;Wuhan Municipal Construction Group Co.,Ltd.,Wuhan,Hubei 430023,China;The Southern Engineering Co.Ltd.of China Railway Construction Electrification Bureau Group,Wuhan,Hubei 430070,China)

机构地区：[1]武汉工程大学土木工程与建筑学院,湖北武汉430073 [2]武汉市市政建设集团有限公司,湖北武汉430023 [3]中铁建电气化局集团南方工程有限公司,湖北武汉430070

出　　处：《岩土力学》2021年第11期3126-3136,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金面上项目(No.41474113);湖北省建设科技计划项目(2019)。

摘　　要：层状半无限体中瑞利波具有频散特性,不同频率成分瑞利波具有不同可激性。当层状介质下覆半无限体出现充气洞穴时,入射瑞利波遇洞穴发生散射。以层特性参数及厚度与洞穴上方层状介质相同的层状板研究板波传播特性,分析埋深(板厚)/波长比值对板波与入射瑞利波传播特性差异影响。由频率-相速度域洞穴上方数值模拟响应谱得到绕射波频散,与层状板中波频散曲线比较,分析主导绕射波。结果表明:主导绕射波传播特性类似于基阶板波,当入射瑞利波波长大于埋深,洞穴绕射波相速度低于瑞利波速,随着波长减小,逐渐趋于瑞利波速。与基阶瑞利波位移结构相比,绕射波位移随深度变化平缓,变化与分层结构及频率有关。绕射波位移结构导致表面振动能量减弱,不同频率成分,能量减弱程度不同。这种现象是洞穴对表面响应谱扰动主要特征,由偏移距-频率域表面响应谱扰动特征可以预测洞穴在传播方向位置。Rayleigh waves in layered half spaces are dispersive, and the excitabilities of Rayleigh waves are varied at different frequencies. When a cavity full of air is present in the underlying half space, the incident Raleigh waves are scattered at the cavity. In this paper, the waves in the layered plates are studied using the plates with the layer properties and thicknesses equal to those over the cavity. Effects of the ratio of buried depth(plate thickness) to wavelength on differences between the dispersion curves of the diffracted and Rayleigh waves are analyzed. The dispersion of the diffracted waves is obtained from the spectrum of synthetic responses over the cavity in the frequency-phase velocity domain. The dominant diffracted waves are identified by comparing the dispersion curves of the diffracted waves and the plate waves. It is shown from the results that the behavior of the dominant diffracted waves is similar to that of the fundamental plate waves;for the incidence of Rayleigh waves with the wavelength longer than the buried depth, the phase velocity of the diffracted waves is slower than that of Rayleigh waves;with the wavelength of incident Rayleigh waves decreases, the phase velocity of diffracted waves gradually approaches that of Rayleigh waves. Compared with the displacement structure of Rayleigh waves, the variation of the diffracted wave displacement with the depth is flatter. This variation is related to the layer structure and frequency. Due to the displacement structure of the diffracted waves, the vibration energy at the surface is reduced. The level of reduction is varied at different frequency components. This phenomenon is a major feature of the spectral disturbances caused by the presence of a cavity. The locations of a cavity can be identified from the spectral disturbances in the offset-frequency domain.

关 键 词：层状半无限体 频散 散射波 谱扰动 洞穴 

分 类 号：O451[理学—无线电物理]