【摘要】 为研究土洞对岩溶场地地表地震动参数的影响,选取广西桂林市某岩溶场地,分析土洞的存在对地表地震动峰值和频谱的影响。依据场地地震反应分析理论,建立包含土洞与不包含土洞的有限元模型并进行地震反应分析,应用计算结果中1-3层土体表面中心点的地震动,作为原始信号输入,进行FFT(离散傅氏变换的快速算法)转换,得到场地各层土体表面中心点的频谱分析图。分析结果表明:(1)土洞的存在对地表峰值速度和峰值位移影响相对较小,对峰值加速度影响较大,且越上层土体地震动参数受土洞影响越大;(2)包含土洞的加速度频域分布峰值大于不包含土洞的岩溶场地,并且包含土洞与不包含土洞岩溶场地主要(卓越)频率分布在0-5Hz范围,分布较集中,峰值加速度对应的频率在2.5Hz附近。更多还原

【Abstract】 For the research of the influence to the ground motion’s parameters by soil hole in karst ground surface,selection of Guilin in Guangxi karst area,analysis the existence of the soil hole on the surface ground motion peak and the influence of the spectrum. According to the area seismic response analysis theory,the establishment of soil hole and does not include the finite element model of the soil hole and seismic response analysis,the application results in 1- 3 center of soil layer of the surface of the ground motion,as an original signal input,for FFT( fast algorithm of discrete Fourier transform),get the space center of each layer soil surface spectrum analysis diagram. Analysis results show that:( 1) The existence of the soil hole on surface peak velocity and peak displacement effect is relatively small,impact on the peak acceleration is bigger,the ground motion parameter and the upper soil affected by soil caves.( 2) Contains the peak acceleration frequency distribution of the soil hole than does not contain the soil hole in karst area,and contains the soil hole and does not include the soil hole in karst area is mainly( excellent) frequency distribution in the range of 0 to 5 Hz,distribution is relatively concentrated,the peak acceleration of the corresponding frequency in the vicinity of 2. 5 Hz.更多还原