弹性层状半空间中凸起地形对入射平面SH波的放大作用

对Wolf理论进行拓展,使之可解决凸起地形对波的散射问题,进而利用间接边界元法,求解了弹性层状半空间中凸起地形对入射平面SH波的放大作用问题。本文模型的显著特点之一是考虑了层状半空间的动力特性以及层状半空间和凸起地形的阻尼;特点之二是计算精度高。文中以基岩上单一土层中半圆凸起地形对入射平面SH波的放大作用为例进行了数值计算分析。研究表明,基岩上单一土层中凸起地形对入射平面SH波放大作用和均匀半空间中凸起地形有着本质的差别;土层动力特性不仅影响凸起地形地表位移的幅值,还会影响地表位移的频谱;阻尼会显著降低凸起地形对高频波的放大作用。

Surface motion of a hill in layered half-space subjected to incident plane SH waves

Wolf's theory is extended to solve the problem of wave scattering by a hill.The indirect boundary element method(IBEM) is used to calculate the amplification of incident plane SH waves by a hill in layered half-space.One advantage of the model is that it includes the dynamic characteristics of the layered half-space and the damping of the layered half-space and the hill,and another is its high precision in the calculation.The numerical analyses are performed by taking the amplification of incident plane SH waves by a hill in one layer over half-space as an example.The results show that there exist distinct differences between the wave amplification by a hill in one layer over half-space and that in homogeneous half-space;the dynamic characteristics of the soil layer affect not only the surface displacement amplitudes of a hill but also their frequency spectra;the damping decreases the amplification of the incident waves of high frequencies.