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基岩地震动的确定是场地地震反应与土-结构动力相互作用分析的关键步骤之一。本文首先对通过反演获取基岩地震波的波动法和有限元法做了简要比较,阐述了在深覆盖土层地震波反演分析中频率截断的重要性。然后,以上海某深覆盖土层场地为例,分别采用波动法和有限元法对不同深度土层(包括土层10 m深处、土层20 m深处、土层45 m深处、土层140m深处和土层280m深处)的加速度传递函数进行了计算分析与比较,结果表明,深覆盖土层的加速度传递函数的模在高频处趋近于零。在对传递函数深入分析的基础上,分别选用普通El Centro波和长周期TCU115波进行了反演分析,探讨了不同类型地震波在深覆盖土层反演中的频率截断问题,得到了有应用价值的结果。
The determination of bedrock ground motion is one of the key steps in the field seismic response and soil-structure dynamic interaction analysis. In this paper, firstly, a brief comparison is made between the wave method and the finite element method for seismic acquisition of bedrock by inversion, and the importance of frequency truncation in seismic wave inversion analysis of deep overburden is illustrated. Then, taking a deep overburden site in Shanghai as an example, we use wave method and finite element method respectively to study the effects of different depths of soil layers (including depth of 10 m, depth of 20 m, depth of 45 m, Layer depth of 140m and depth of 280m) were calculated and analyzed. The results show that the moduli of acceleration transfer function in deep overburden reach near zero at high frequency. Based on the deep analysis of the transfer function, the ordinary El Centro wave and the long-period TCU 115 wave are respectively selected for inversion analysis, and the frequency truncation problems of different types of seismic waves in the inversion of deep overburden soil are discussed, and the application value is obtained the result of.