地震表面波周期性波屏障的设计与性能研究

发布时间：2018-11-14 14:05

【摘要】：地震表面波振幅大,传播距离远,频率较低,一般在20Hz以下,对结构的危害很大。如何采用新技术来有效地降低震害,是科研工作者的迫切任务。地震表面波周期性波屏障作为一种有效的隔震措施,能够对特定频率范围内的低频地震动进行人为设计和调整结构参数,使带隙频率覆盖地震动主频范围,从而达到较好的隔震效果。对地震表面波周期性波屏障设计和性能研究具有理论和工程应用价值。本文基于周期结构带隙设计思想,针对破坏性较强的半空间自由表面Rayleigh波,即地震表面波,尤其是20Hz以下的低频表面波,设计了三种新型表面波屏障,即周期立柱式表面波屏障、双向周期格栅式表面波屏障和三向周期格栅式表面波屏障,并利用COMSOL MULTIPHYSICS有限元软件分别对三种表面波屏障的能带结构和频率响应以及位移模式进行了数值模拟,给出了全模态能带结构中表面波模式的提取方法,分析了带隙的形成机理,探讨了波屏障结构参数对隔震性能的影响。研究结果表明:1、周期立柱式表面波屏障带隙形成机理为局域共振型,立柱的埋入深度、立柱的高度、立柱的半径能够有效的调节带隙的宽度。立柱埋入深度的增加和立柱半径增大都会使带隙上下缘位置升高,立柱高度增加会降低带隙频率位置。2、双向周期格栅式表面波屏障带隙形成机理为局域共振型,栅板的几何参数能够有效的调节带隙的宽度,材料参数对带隙频率范围影响较大,栅板密度增加、土体密度增加和土体弹性模量减小都会降低带隙的频率位置。3、三向周期格栅式表面波屏障带隙形成机理为局域共振型,横向栅板高度对带隙频率范围影响较大,横向栅板位置对带隙频率范围影响很小。横向栅板的密度、土体的密度和土体弹性模量对带隙频率范围影响较大。4、利用声线和模态分析相结合的方法,可以将半埋入式表面波屏障的表面波模式从全模态能带结构中分离。5、三种新型表面波屏障带隙频率范围均在20Hz以下,其中,立柱式表面波屏障的带隙宽度较窄,三向周期表面波屏障表面波带隙起止频率比双向周期表面波屏障表面波带隙起止频率低,带隙宽度比双向周期表面波屏障表面波带隙宽度略窄。
[Abstract]:The seismic surface wave has large amplitude, long propagation distance and low frequency. It is generally below 20Hz, which is harmful to the structure. How to adopt new technology to effectively reduce earthquake damage is an urgent task for researchers. As an effective isolation measure, the seismic surface wave periodic wave barrier can artificially design and adjust the structural parameters of low frequency ground motion in the specific frequency range, so that the band gap frequency can cover the main frequency range of ground motion. In order to achieve a better isolation effect. The research on the design and performance of seismic surface wave periodic wave barrier has theoretical and engineering application value. Based on the idea of band gap design of periodic structures, three new types of surface wave barriers are designed for the destructive half-space free surface Rayleigh waves, that is, seismic surface waves, especially the low-frequency surface waves below 20Hz. That is, periodic vertical column type surface wave barrier, bidirectional periodic grid type surface wave barrier and three direction periodic grid type surface wave barrier, The energy band structure, frequency response and displacement mode of three kinds of surface wave barrier are numerically simulated by using COMSOL MULTIPHYSICS finite element software. The extraction method of the surface wave mode in the full-mode energy band structure is given, and the formation mechanism of the band gap is analyzed. The influence of the structural parameters of the wave barrier on the isolation performance is discussed. The results show that: 1. The formation mechanism of the band gap of periodic column type surface wave barrier is local resonance type. The embedded depth of the column, the height of the column and the radius of the column can effectively adjust the width of the band gap. The increase of the depth and radius of the column will increase the position of the upper and lower edge of the band gap, and the height of the column will decrease the frequency of the band gap. 2. The formation mechanism of the band-gap of the bidirectional periodic grid surface wave barrier is local resonance. The geometric parameters of the grid plate can effectively adjust the width of the band gap. The material parameters have a great influence on the frequency range of the band gap. The increase of the density of the grid plate, the increase of the soil density and the decrease of the elastic modulus of the soil will decrease the frequency position of the band gap. The formation mechanism of the band gap of the three direction periodic grid type surface wave barrier is local resonance. The height of the transverse grid has a great influence on the frequency range of the band gap, while the position of the transverse grid has little effect on the frequency range of the band gap. The density of transverse grid, the density of soil and the elastic modulus of soil have great influence on the frequency range of band gap. The surface wave mode of the semi-submerged surface wave barrier can be separated from the full-mode energy band structure. 5. The band gap frequency range of the three new types of surface wave barrier is below 20Hz, among which the band gap width of the column type surface wave barrier is narrow. The starting and stopping frequency of surface wave band gap of three direction periodic surface wave barrier is lower than that of bidirectional periodic surface wave barrier, and the width of band gap is a little narrower than that of bidirectional periodic surface wave barrier.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU352.1

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