地震波反演与地下结构的动力响应分析
SEISMIC WAVES INVERSION AND DYNAMIC RESPONSE ANALYSIS OF UNDERGROUND STRUCTURES
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摘要: 为获取软土场地的基岩地震波时程,该文利用波动法和等效线性化技术,通过自编地震波反演程序,以上海某软土场地为例,反演求得了六条基岩处的地震波时程,并进行了精度验证。在此基础上,以某地铁车站结构为工程背景,采用ANSYS程序建立土-结构相互作用体系分析模型,选取El-Centro地震波的反演基岩波作为输入,对软土场地中的地下结构进行了动力响应分析。结果表明:该文的软土场地地震波反演计算可获得较高精度的基岩地震波时程;对于不同类型的地震波,地面地震波峰值与基岩地震波峰值的比值有较大差异;与地上结构相比,地下结构虽然其水平位移反应值较大,但结构顶板与底板之间的水平向相对位移并不大。Abstract: In order to obtain the seismic wave of the bedrock in a thick soft soil site, the inversion program based on wave propagation theory and equivalent linearization technique is developed. Six bedrock acceleration time histories under typical Shanghai soft soil are inverted by a self-compiled inversion program, and they are validated by the comparison with forwarded simulation. Then, the finite element model of the subway station considering soil-structure dynamic interaction is established, and the bedrock time history inverted El-Centro wave is selected as input motion to conduct the dynamic response analysis of an underground structure in a soft soil site. The analysis results show that: the seismic wave inversion program can attain the precise inverted bedrock motions; for different types of seismic waves, the ratios of peak surface acceleration to bedrock acceleration are significantly different; compared to superstructures, an underground structure has a larger horizontal displacement, but the relative horizontal displacement between top and bottom plates is small.