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为研究地震中Rayleigh波对地表浅层土体的响应特征,针对Lamb问题的模型工况开展有限元动力分析,验证有限元法精确模拟Rayleigh波作用效应的可行性。以厦门地区浅层的素填土及粉质黏土为研究对象,采用摩尔-库仑本构模型,结合Rayleigh阻尼,并在模型的底部和边界上采用黏性边界,采用有限元法考察Rayleigh阻尼中质量比例阻尼系数α和刚度比例阻尼系数β对响应特征的影响规律。研究表明:有限元动力分析可以模拟Rayleigh波作用下的远场动力问题,能取得与Lamb问题解析解较为一致的解答,同时还可以捕捉P波和S波的到达时间;α的变化对素填土和粉质黏土中Rayleigh波的传播特征基本没有影响;β的变化不会影响传播速度,但影响波的振幅,β是Rayleigh阻尼的主控参数。该结论可为采用有限元法研究Rayleigh波对浅埋结构物的地震动力响应提供理论基础和科学依据。
In order to study the response characteristics of Rayleigh waves to the shallow soil layer in the earthquakes, a finite element dynamic analysis is carried out based on Lamb model to verify the feasibility of the finite element method to accurately simulate the Rayleigh wave effect. Taking shallow plain earth and silty clay in Xiamen as the research object, the Mohr-Coulomb constitutive model, Rayleigh damping and the viscous boundary are used at the bottom and boundary of the model. The finite element method Effect of mass ratio damping coefficient α and stiffness ratio damping coefficient β on response characteristics. The results show that the finite element dynamic analysis can simulate the far-field dynamic problem under the action of Rayleigh wave and obtain a more consistent solution to the analytical solution of the Lamb problem. At the same time, the arrival time of P-wave and S-wave can be captured. The propagation characteristics of Rayleigh waves in soil and silty clay are basically unaffected; the change of β does not affect the propagation velocity, but affects the amplitude of the wave, and β is the dominant parameter of Rayleigh damping. This conclusion can provide a theoretical basis and a scientific basis for using the finite element method to study the seismic response of Rayleigh waves to shallow buried structures.