Simulation of Toppling Columns in Archaeoseismology
Simulation of Toppling Columns in Archaeoseismology
复制标题
考古地震学中柱倒塌的模拟
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
K. Hinzen
中科院分区：
文献类型：
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作者：
K. Hinzen
从现代地震学的早期开始，人们就利用地震后倒塌的文物，如墓碑和单柱，来推断特定地点的地面运动参数。人工制品通常被视为刚体。后来，刚性块体运动理论也被应用于不稳定平衡的岩石在地震中倒塌。虽然单个摇摆块的运动可以用解析的方法来描述，但滑动-摇摆运动、弹跳和多块系统需要用数值方法来描述。我们使用具有粘弹性耦合力的多个刚性块体模型，结合完整的三维地面运动（测量和合成）来分析建筑单元的动力响应，与考古地震研究相关。首先，将数值模拟结果与解析确定的单个矩形块的摇摆运动进行比较，验证了数值模拟结果。对耦合力的刚度和阻尼参数进行了调整，使其符合大理岩块的模拟实验结果。采用整体柱和七鼓柱模型，研究了几何形状和摩擦力对柱体倾倒性能的影响。在这项研究中解决的主要问题是，倒塌的柱子是否能清楚地指示震源的后方位角。来自29个强震记录的输入运动表明，下落方向与后方位之间的相关性很小。明确方向的水平地面运动倾向于在横向上推翻柱子。更复杂的地面运动导致近似随机的下落方向。摩擦系数对下降方向的影响较小。不同震源机制的两次地震的合成地震动表现出向震源方向和远离震源方向以及横向方向的倾倒方向。然而，要从倒转方向的反演中推断出可靠的震源位置并不是一件容易的事。
Abstract Since the early days of modern seismology, toppled artifacts such as tombstones and single columns have been used in the aftermath of earthquakes to deduce parameters of site-specific ground motions. The artifacts were generally treated as rigid bodies. Later, the theory of rigid block movements was also applied to precariously balanced rocks toppled by earthquakes. While the movements of a single rocking block can be described analytically, slide-rocking movements, bouncing, and multiple block systems require a numerical approach. We use multiple rigid block models with viscoelastic coupling forces in combination with full 3D ground motions (measured and synthetic) to analyze the dynamic response of building elements, relevant for archaeoseismological studies. First, the numeric modeling results are verified by comparison with analytically determined rocking motions of a single rectangular block. Stiffness and damping parameters of the coupling forces are adjusted to results from analog experiments with a rocking marble block. A model of a monolithic column and one consisting of seven drums is used to test the influence of the geometry and friction on the toppling behavior. The main question addressed in this study is whether toppled columns give a clear indication of the back azimuth toward the earthquake source. Input motion from 29 strong-motion records indicates little correlation between downfall directions and back azimuth. Clearly directed horizontal ground movements tend to topple the columns in the transverse direction. More complex ground motions result in quasi-random downfall directions. The friction coefficients have a minor influence on the downfall directions. Synthetic ground motions for two earthquakes with different source mechanism show toppling directions toward and away from the source as well as in the transverse bearing. However, it is not straightforward to deduce a reliable source location from the inversion of the toppling directions.