基于强震台网记录的地震波反演精度分析

Precision analysis of seismic wave inversion method based on strong seismic records

为探究基于一维波动理论的地震波反演计算精度,利用日本Ki K-net台网数据,选取了145组地震动加速度记录及相关场地资料,利用等效线性化方法模拟土的非线性,通过对地表波反演计算所得基岩波与实测基岩地震动记录的比较,分析了基于一维波动理论的地震波反演的计算精度,讨论了场地条件、地表波频谱特性以及加速度峰值对反演精度的影响。算例结果表明:基于一维波动理论的地震波反演计算结果总体上要大于实测的基岩地震动记录;场地条件对地震波反演的计算精度影响较大,在算例中,计算误差随Ⅳ类场地至Ⅰ类场地土层变"硬"而减小,软弱夹层的存在亦会显著增大计算误差;当地表波加速度峰值小于0. 1g时,基于一维波动理论的地震波反演计算精度较高。

In order to explore the accuracy of seismic wave inversion calculation based on one-dimensional wave theory,145 sets of ground motion acceleration records and related site data were selected by using Ki K-net network data of Japan.The nonlinearity of soil was simulated by equivalent linearization method. The comparison between the ground wave inversion calculated by surface wave inversion and the ground motion record of the measured bedrock was analyzed. The calculation accuracy of seismic wave inversion based on one-dimensional wave theory was analyzed. The effect of the site conditions,the characteristics of surface wave spectrum and the accuracy of the acceleration peak on the calculation accuracy were discussed. The results of the example show that the seismic wave inversion calculation results based on the one-dimensional wave theory are larger than the measured bedrock ground motion records;the site conditions have a great influence on the calculation accuracy of seismic wave inversion. In the example,the calculation error decreases with the soil layer of Class Ⅳ to Class Ⅰ site becomes ' hard',the existence of weak interlayer will also significantly increase the calculation error;when the local table wave acceleration peak is less than 0. 1g,the seismic wave calculation accuracy based on one-dimensional wave theory is high.