非饱和土地基中波阻板隔振屏障对P波的隔离效应

ISOLATION EFFECT OF WAVE IMPEDING BARRIER ON P-WAVE IN UNSATURATED GROUND FOUNDATION

  • 摘要: 波阻板隔振屏障常常用来降低振源振动,但传统的波阻板隔振研究仅限制在单相弹性或者两相饱和土地基中。而自然中的土体通常是三相非饱和土,弹性波在非饱和土介质中的传播特性完全不同于单相弹性介质或两相饱和多孔介质。因此,该文建立了基岩上覆非饱和土地基中波阻板屏障的数学模型,基于非饱和多孔介质和弹性介质中的波动理论,研究了三相非饱和土地基中波阻板对P波的隔离效应。根据Helmholtz原理,获得了P波入射下非饱和土地基中设置波阻板后地表位移解答。分析研究了入射角度、入射频率、饱和度以及波阻板的剪切模量、厚度、埋深等物理力学参数对非饱和土地基中波阻板隔振效果的影响规律。结果表明:饱和度对波阻板的隔振效果影响显著,波阻板的隔振效果随着饱和度的增大先提高后降低,随入射角的增加先降低后提高;波阻板隔振屏障对高架引起的振动隔振效果明显,对中频、高频隔振局限性大、范围小,并存在临界厚度;波阻板隔振效果随埋深和剪切模量的增大而增大。

     

    Abstract: Wave impeding barrier (WIB) were often used to reduce source vibration, but the research on traditional WIB vibration isolation was limited to single-phase elastic or two-phase saturated foundations. While the soil in nature is usually tri-phase unsaturated soil, the propagation characteristics of elastic waves in unsaturated soil media are different from single-phase elastic media or two-phase saturated porous media. Consequently, this study establishes a mathematical model that installing WIB in unsaturated foundation overlying bedrock. Based on the wave theory in unsaturated porous medium and elastic medium, the isolation effect of WIB on P-wave in tri-phase unsaturated foundation is studied; the solutions of surface displacement after installing WIB in an unsaturated foundation under P-wave incidence are obtained according to the Helmholtz principle; and the effect of some key physical and mechanical parameters are analyzed such as incidence angle, incidence frequency, saturation and shear modulus, thickness and burial depth of the WIB on the vibration isolation effect of WIB in the unsaturated foundation. The results showed that saturation has a significant effect on the vibration isolation of the WIB; that the vibration isolation effect of the WIB increases and then decreases with increasing saturation; that its vibration isolation effect decreases and then increases with increasing incidence angle; that the WIB is effective in isolating vibration caused by elevated, but it is limited and narrow for medium- and high-frequency, and there existed a critical thickness; and that the vibration isolation effect of WIB can be enhanced with the increasing burial depth and shear modulus.

     

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