场地土层模型参数的地震动记录反演方法

考虑场地土层不同物理参数的综合反演,改进了水平与竖向谱比(Horizontal-to-Vertical Spectral Ratio,简称HVSR)混合全局优化反演方法,进一步通过土层的S、P波波速、厚度、泊松比、密度和S、P波品质因子等土层参数反演的敏感性分析,形成了可同时反演场地土层厚度及剪切波速的混合全局优化反演方法.以美国GVDA和日本IWTH27竖向强震动观测台阵为例,分别以理论HVSR及加速度观测记录获得的HVSR曲线为目标,反演获得了场地浅层速度结构,并与观测台阵场地钻孔揭示的土层模型进行比较,验证了发展的反演方法的合理性和适用性.本文研究表明,基于地震加速度记录的HVSR全局优化反演方法是获取场地土层速度结构的一种有效的途径.

Inversion for velocity structure of soil layers by seismic acceleration records

Considering the comprehensive inversion of different physical parameters of soil layers,the hybrid global optimization inversion algorithm of Horizontal-to-Vertical Spectral Ratio (HVSR) was improved. Furthermore, through a sensitivity analysis of inversion parameters of soil layers such as S and P wave velocities, thickness, Poisson's ratio, density and S and P wave quality factors, a hybrid global optimization inversion algorithm was developed for simultaneous inversion for thicknesses and shear wave velocities of soil layers. Taking two vertical borehole strong motion arrays, the Garner Valley Downhole Array (GVDA) in U.S. and the KiK-net Vertical Array IWTH27 in Japan as examples, the velocity structures of the arrays were inverted from the theoretical and observed HVSRs, respectively, and compared with the model of soil layers revealed by drilling holes in the vertical borehole strong motion array sites, thus the rationality and applicability of the developed inversion algorithm were verified. The results in this study show that the HVSR global optimization inversion algorithm based on seismic acceleration records is an effective way to obtain velocity structure of soil beds in the site.