表层土剪切波速的不确定性对地表设计谱平台值的影响

Effects of Uncertainties of Shear Wave Velocity of Soil Surface Layer on Platform Value of Surface Design Response Spectra

土层剪切波速对地表反应谱有重要的影响。选取构建了不同场地类别的235个场地地震反应模型,人工合成了12条强弱及频谱特性不同的加速度时程,运用一维土层地震反应的等效线性化波动方法,研究了不同地震动输入下表层土剪切波速的不确定性对设计谱平台值的影响,统计给出了表层土剪切波速的变异率与地表设计反应谱平台值间的经验公式。结果表明:地表设计反应谱平台值与表层土剪切波速的变异率呈负相关关系,即随表层土剪切波速变异率的增大而减小;不同地震波输入条件下各类场地类别地表设计谱平台高度与表层土剪切波速变异率的数学模型为一阶指数函数。

The shear wave velocity of soils has important influences on response spectra. The 235 models of seismic site response, which belong to different site categories, are selected and constructed. And 12 pieces of varying amplitudes and frequency content acceleration time history are artificially made. The effects of the shear wave velocity of soil surface layer on design spectra platform are studied using one-dimensional equivalent linear wave propagation method of soil earthquake response, the functions between platform value of surface design response spectra and the variation rate of shear wave velocity are statistically provided. The results show that there is negative relationship between platform value of surface design response spectra and the variation rate of shear wave velocity and their mathematical model is a one-order exponential function.