【摘要】 以汶川极震区青川东河口地震滑坡为典型实例,首先从滑坡地脉动现场测试的频谱特征曲线分析可得,卓越频率在1~3Hz范围内,且NS向的谱比值最大。其次,通过对东河口滑坡单一结构、二元结构两种弹性模型输入不同中心频率0.5Hz~4Hz的Ricker子波,发现二元结构的PGA放大系数普遍大于单一结构,同时中心频率较低时,滑坡PGA放大系数分布范围较广,相反,较高中心频率的PGA放大系数仅集中在坡顶和两侧山脊处,表明:中心频率高低对于PGA放大系数影响范围也不同。最后,对东河口地震滑坡弹塑性模型输入汶川地震绵竹清平台站加速度记录,根据监测点残余变形,认为滑坡破坏发生在6.5s处,并结合输入地震波频率在此时刻出现较高傅立叶谱值,表明东河口地震滑坡的发生是由高频谱值输入地震波触发。本研究有助于从地层场地效应角度理解斜坡动力失稳过程。更多还原

【Abstract】 The microtremors were firstly carried out along the boundary of Donghekou rockslide after Wenchuan earthquake,whose spectral characteristic curves showed that the predominant frequency was within the range of 1 ~ 3Hz,and the spectral ratio maximum occurred in NS direction. Secondly,the selected central frequencies of Ricker wavelets were input into the 2-layer conceptualization elastic model as well as the homogenous one. It is found that the PGA amplification of 2-layer model are higher than the homogenous one,and the range of PGA amplification is wider when the input central frequencies are lower,and the PGA amplification with higher central frequencies just concentrates on the crest and ridges of the slope. It shows that different central frequencies result in different ranges of the PGA amplification. Finally,an elastic-plastic model with the input Wenchuan acceleration records at Qingping station was used to analyze the relation between input waves of frequencies and failure process. According to the residual displacement of monitoring points,the failure time of 6. 5s is determined. Meanwhile,according to high spectral values near the time of 6. 5s,it shows the input wave with higher spectral values( Fourier values) will cause the rockslide. This study will help to raise awareness of the process of rockslide based on stratigraphic site effect.更多还原