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利用二维显式有限元场地地震反应分析程序,把不同频谱特性的地震动作为输入基岩的SH波,探讨了阶跃基岩覆盖土层场地地震动空间分布特征,重点研究了覆盖土层厚度和土层性状对场地地表加速度峰值和反应谱的影响。研究表明:对于阶跃基岩覆盖土层场地,覆盖土层厚度变化对相应区域地表地震反应有较为明显的影响,对土层厚度不变区域的地表地震反应影响不明显。土层性状对阶跃基岩覆盖土层场地地表的加速度峰值和反应谱均有重要的影响。软土和上软土下硬土组合土层场地地表的加速度峰值要比硬土场地地表上的大。软土场地中反应谱的峰值要比硬土场地中反应谱的峰值大,硬土场地反应谱峰值对应的周期较短,软土场地反应谱峰值对应的周期较长。土层性状对地震动反应谱的影响,主要体现在短周期分量上。
Based on the two-dimensional explicit finite element method for seismic response analysis of site, the seismic wave with different spectral characteristics is used as the SH wave input into the bedrock, and the spatial distribution of ground motion in the bedrock-covered soil layer is discussed. Effects of Thickness and Soil Properties on Peak Acceleration and Response Spectra of Ground Surface. The results show that the change of cover soil thickness has obvious influence on the surface seismic response of the corresponding area for the step-bedrock-covered soil, and has no obvious effect on the surface seismic response in the area of constant soil thickness. Soil properties have an important effect on the peak acceleration and response spectrum of the ground surface covered by steep bedrock. Soft soil and soft soil under the combination of soil layer soil surface acceleration peak is greater than the hard surface of the ground. The peak value of the response spectrum in the soft soil field is larger than the peak value of the response spectrum in the hard soil field, the period corresponding to the peak of the response spectrum in the hard soil field is short, and the peak corresponding to the peak of the response spectrum in the soft soil site has a longer period. The influence of soil properties on the seismic response spectrum is mainly reflected in the short-period component.