地震基岩面的选取对深厚场地地表地震动参数的影响

发布时间：2019-03-07 21:36

【摘要】：地震基岩面的选取对场地设计地震动参数取值的合理性有重要影响。以苏州城区的钻孔剖面为研究对象,选取剪切波速介于400~800 m/s的9个土层顶面作为地震基岩面,采用等效线性方法考虑土的非线性特性,采用一维波传法分析地震基岩面的选取对地表地震动特性的影响。结果表明:1地表峰值加速度PGA随地震基岩面剪切波速的增大而增大,PGA的增大幅度随输入地震动强度的增大而减小;2地表加速度反应谱放大系数?谱谱值也随地震基岩面土层剪切波速的增大而增大,且?谱谱值随输入地震动强度的增大而减小;对于中强地震的近场地震动作用,基岩面深度对周期小于1.0 s的?谱谱值的影响较大;而对于特大地震的远场地震动作用,基岩面深度对周期小于4.0 s的?谱谱值均有较大影响;3远场地震动作用时的?谱谱值明显大于近场地震动作用的?谱谱值;4取剪切波速不小于700m/s的土层顶面为地震基岩面较为适宜。
[Abstract]:The selection of seismic bedrock surface has an important influence on the rationality of site design ground motion parameters. Taking the borehole profile in Suzhou city as the research object, nine soil top surfaces with shear wave velocity between 400 and 800 m / s are selected as seismic bedrock surface, and the nonlinear characteristics of soil are considered by equivalent linear method. The one-dimensional wave propagation method is used to analyze the influence of the selection of seismic bedrock surface on the seismic ground motion characteristics. The results show that: (1) the surface peak acceleration (PGA) increases with the increase of shear wave velocity, and the increase of PGA decreases with the increase of input seismic ground motion strength; (2) the amplification factor of surface acceleration response spectrum; The spectral value also increases with the increase of shear wave velocity in the soil layer of the seismic bedrock, and? The spectral values decrease with the increase of the intensity of the input ground motion, and for the near-site seismic action of the moderate strong earthquake, the depth of the bedrock surface to the period less than 1.0 s? The influence of spectral value is greater, but for the far-site seismic action of large earthquake, the depth of bedrock surface to the period less than 4.0 s? The spectral values have a great influence on them. (3) in far-field vibration? The spectral value is obviously greater than that of near-site motion? If the shear wave velocity is not less than 700m/s, it is more suitable to take the top surface of the soil layer as the seismic bedrock surface.
【作者单位】：南京工业大学岩土工程研究所;江苏省土木工程防震技术研究中心;江苏省地震局;
【基金】：国家自然科学基金项目(51378258)
【分类号】：TU435

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