SH波入射时软弱夹层的减震特性及影响因素分析  

Vibration Attenuation Performance of Soft Interlayer under Incident SH Waves and Influential Factors

作　　者：王芳其[1] 李亚勇[2] 吕志涛[2] 靳晓光[2] 

机构地区：[1]招商局重庆交通科研设计院有限公司,重庆400060 [2]重庆大学土木工程学院,重庆400045

出　　处：《防灾减灾工程学报》2016年第1期31-37,共7页Journal of Disaster Prevention and Mitigation Engineering

基　　金：重庆市应用开发项目(CSTC2013YYKFA3003)资助

摘　　要：在弹性介质假定和忽略反射波影响的条件下,从透射波振幅和能量的角度,研究了SH波入射时入射角与波阻比对软弱夹层减震特性的影响。通过非线性弹塑性动力计算,探讨了软弱夹层的埋深与层厚对其减震特性的影响。研究结果表明,随着入射角的增大,透过软弱夹层进入上部普通层的波的振幅和能量先缓慢增大至与入射波相同,然后快速减小至0,整体上小于入射波;存在最不利入射角,它是波速比与密度比的函数,当SH波以此角度入射时,夹层的底面和顶面均不存在反射波,入射波全部透过夹层;软弱夹层与普通层的波阻比越小,透过夹层进入普通层的波的振幅和能量越低,夹层的减震效果越好,但此时夹层自身的震动也越剧烈。随着入射波波长的增加,软弱夹层发挥减震作用所需的临界埋深增大,且埋深在0.2倍普通层剪切波波长左右时,减震效果达到最佳;软弱夹层的减震效果并不随着层厚增加单调变化。From the aspect of amplitude and energy of transmitted wave,the influence of incident angle and acoustic impedance ratio of SH waves on the vibration attenuation performance of soft interlayer is studied on condition that the medium is elastic and the reflected wave is neglected.Non-linear elasticplastic dynamic calculation is conducted to analyze the influence of the buried depth and thickness of the soft interlayer on the vibration attenuation performance.As a result,with the increase of incident angle,firstly the amplitude and the energy of the wave that transmits through the soft interlayer into the regular layer gradually increase and then rapidly decrease to zero.There exists a most unfavorable incident angle that is a function of velocity ratio and density ratio.When the SH wave incidents with the most unfavorable angle,no reflected wave occurs at the bottom and top of the soft interlayer,and the incident wave will totally transmit through the interlayer.The lower the acoustic impedance ratio of the soft interlayer to the regular layer is,the better the vibration attenuation performance of the soft interlayer is.However,the vibration of the soft interlayer will be more severe.In order to guarantee the damping effect of the soft interlayer,the critical buried depth of the soft interlayer increases with the wavelength of the incident wave.The damping effect will be the best when the buried depth is approximate to 20 percent of the wavelength of the shear wave in regular layer.It should be noted that the damping effect does not monotonously increase with the thickness of the soft interlayer.

关 键 词：软弱夹层 减震特性 入射角 波阻比 埋深 

分 类 号：P315.9[天文地球—地震学]