平台地形对地震地面运动特征周期值的影响

本文人工合成了36条代表不同频谱特性的地震动,构造了简单的平台地形,并利用人工合成地震动作为平台地形计算输入地震波,获得了地表观测点的时程和反应谱.在此基础上,分析了具有不同高度、侧向坡降和介质阻尼等的平台地形对地震动特征周期值的影响.研究的结果表明:当平台高度与入射地震波优势波长相比较小时,平台的高度、侧向坡降、阻尼比等对地震动特征周期值的影响不大,此时单个平台地形地表地震动的特征周期主要依赖于入射地震动的特征周期,而且一般比入射地震动的特征周期略有增大;当平台高度与入射地震波优势波长相比较大时,平台高度对地表地震动特征周期影响较大.

Effect of Protruding Topography on Characteristic Period of Ground Motion

36 artificial ground motions with different spectrum properties and computing models of protruding topography are constructed in this paper. Then, we use the artificial seismic waves as basic excitation and get the acceleration time history and response spectra of ground motions on free surface of protruding topography. The effect of different height, different slope degradation, and different damping ratio on characteristic period of ground motion are studied. The results show that when the size of protruding topography is less than predominant wavelength, the effects of height, slope degradation and damping ration are weak. The characteristic period of ground motion mainly depends on and is appreciably bigger than that of incidence. When the size of protruding topography is larger than predominant wavelength, effects become remarkable.