与已知场点相关的地震动场模拟研究

提出了一种与已知场点相关地震动场模型。将工程频段(0~25 Hz)分成若干个互不重叠的子段,在每个子频段内将地震动看作面波和体波的叠加;其次在每个子频段内确定影响合成地震动幅值谱的关键因素并将其引入模型中,使每个子频段的合成地震动幅值谱、功率谱和已知幅值谱、功率谱一致;再次由相位差谱频数分布与地震动强度包络的相似性,将决定地震动强度非平稳的关键因素即相位差谱引入到模型中,使合成地震动和已知地震动波形相似;最后,由模型中的频散曲线和距离参数描述不同场点之间的相干性,将合成地震动扩展到地震动场模型。El Centro地震波场点地震动场算例表明,模型不仅可以实现合成地震动场功率谱和已知场点完全一致,而且相干性合理,可以用于工程分析。

Simulation of ground motion field related to known field points

Here, an earthquake ground motion field model related to known field points was proposed.Firstly, the engineering frequency band (0- 25 Hz) was divided into several non-overlapping segments as sub frequency bands, and within each sub-band, ground motion was taken as superposition of surface wave and body one.Then, key factors affecting amplitude value spectrum of synthetic ground motion in each sub-band were determined and introduced into the proposed model so that both amplitude value spectrum and power spectrum of synthetic ground motion within each sub-band were consistent to the known ones.Furthermore, according to the similarity between frequency distribution of phase difference spectrum and envelope of ground motion intensity, the phase difference spectrum as a key factor to determine the non-stationary of ground motion intensity was introduced into the proposed model to make the waveform of the synthetic ground motion similar to that of the known ground motion.Finally, the coherence among different field points was described by the frequency dispersion curve and distance parameters in the model to extend synthetic ground motion to the ground motion field model.The example simulation results of the ground motion field related to El Centro seismic wave field points showed that the proposed model can not only realize the power spectrum of the synthetic ground motion field being full consistent to those of El Centro seismic wave field points, but also the coherence is reasonable, so the proposed model can be applied in engineering analysis.