基于小波包和反应谱的黄土边坡动力特征研究
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王尚(1996-),男,山东菏泽人,在读硕士,主要从事岩土与隧道方向的学习与研究工作。E-mail:1134409205@qq.com

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国家自然科学基金(51968041,41562013);兰州交通大学“百名青年优秀人才培养计划”基金项目(2017150)


Dynamic characteristics of loess slopes based on wavelet packet and response spectrum
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    摘要:

    为研究黄土边坡在地震动力作用下的动力响应特征,以宝兰客专沿线某天然黄土边坡为工程背景,建立1∶20缩尺的黄土边坡试验模型。通过大型振动台试验,采用时程分析和小波包、反应谱分析相结合的方法,在模型底部振动台上输入地震动荷载,分析黄土边坡结构在地震动荷载下加速度信号第一频段能量占比(E1)、第二频段能量占比(E2)、特征周期、反应谱幅值、峰值加速度(PGA)和加速度放大系数(AFA)的变化规律。结果表明:根据E1.E2转化规律,弹性阶段可以细分为挤压密实阶段和密实阶段,E1+E2的最大值位于边坡顶部位置。在弹塑性阶段,同种类型地震波不同地震烈度下到达特征周期的时间基本不变,ElCentro波到达特征周期的时间滞后于汶川汤峪波,且其加速度、速度反应谱幅值也略小。模型在水平方向上存在PGA及AFA放大效应,PGA及AFA沿水平方向放大效应按照大小排序为:破坏阶段>塑性阶段>弹性阶段。地震过程中距离坡面越近的位置越容易被破坏和先破坏,验证了地震过程中“鞭梢效应”的存在。

    Abstract:

    To study the dynamic response characteristics of loess slopes under dynamic seismic action, a 1:20 scaled loess slope test model was established based on a natural loess slope along the Baoji-Lanzhou passenger dedicated line. Through large scale shaking table test and other methods such as time history analysis, wavelet packet analysis, and response spectrum analysis, we analyzed the variation rules of the first frequency band energy proportion (E1), second frequency band energy proportion (E2), characteristic period, response spectrum amplitude, peak acceleration (PGA), and amplification factor of acceleration (AFA) of the loess slope structure under seismic load . Results show that according to the transformation law of E1 and E2,the maximum value of E1+E2 is located at the top of the slope. In the elastoplastic stage, the time for the same seismic wave to reach the characteristic period under different seismic intensities is basically the same; the time for the El Centro wave to reach the characteristic period lags behind that of the Wenchuan Tangyu wave, and the amplitudes of its acceleration and velocity response spectrum are slightly smaller. The PGA and AFA amplification effects in the horizontal direction of the model are in the order of their magnitudes: failure stage>plastic stage>elastic stage. During the earthquake, the location closer to the slope surface is more likely to be destroyed and to be destroyed first, which proves the existence of the“whiplash effect.”It is recommended that anti seismic protection measures should be conducted at the surface and top position of the loess slope in actual projects.

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王尚,梁庆国,乔向进,王丽丽.基于小波包和反应谱的黄土边坡动力特征研究[J].地震工程学报,2023,(1):94-102. WANG Shang, LIANG Qingguo, QIAO Xiangjin, WANG Lili. Dynamic characteristics of loess slopes based on wavelet packet and response spectrum[J]. China Earthquake Engineering Journal,2023,(1):94-102.

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  • 在线发布日期: 2023-01-21