平面P波入射半无限介质内运动空间特征研究

Spatial characteristics of motion in plane P-wave incident semi-infinite medium

针对地震动空间差异问题,采用波动力学与叠加原理相结合的方法研究地震动的空间特征。分别以平面P波在半无限介质内垂直和倾斜入射为例,研究入射波和反射波叠加形成的质点运动空间特征。研究结果显示:以地震波形成质点运动的叠加模式为依据,半无限介质可划分为叠加区和分离区。在叠加区,入射波和反射波由于地震波组合效应对质点运动的持时、峰值以及时程形状产生影响;在分离区,入射波和反射波对质点运动的贡献在时域表现分离特征。地震波叠加模式引起的地震动空间差异较明显,研究地震波叠加模式对地震动空间特征的影响具有重要意义。

Aiming at the problem of spatial diversity of seismic motion, the method of the wave theory combined with the superposition principle was used to study seismic motion’s spatial characteristics. Plane P-wave vertical incident semi-infinite medium and that oblique incident semi-infinite medium, respectively were taken as examples to study spatial characteristics of particle motion caused by superposition of incident wave and reflected one. The results showed that the superposition mode of mass point motions caused by seismic wave is taken as a basis, the semi-infinite medium can be divided into superposition zone and separation one;in superposition zone, incident wave and reflected one affect particle motion’s holding time, peak value and time history shape;in separation zone, the contribution of incident wave and reflected one to particle motion reveals separation features in time domain;seismic motion’s spatial diversity caused by superposition mode of seismic wave is more obvious, so studying effects of superposition mode of seismic wave on spatial characteristics of seismic motion is of great significance.