Sparse Ambient Resonance Measurements Reveal Dynamic Properties of Freestanding Rock Arches
Sparse Ambient Resonance Measurements Reveal Dynamic Properties of Freestanding Rock Arches
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DOI：
10.1029/2020gl087239
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发表时间：
2020-05-16
影响因子：
5.2
通讯作者：
Moore, Jeffrey R.
中科院分区：
文献类型：
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作者：
Geimer, Paul R.;Finnegan, Riley;Moore, Jeffrey R.
独立岩石地貌的动态特性是基本材料和力学参数的函数，便于基于振动的非侵入式结构评估。然而，在文化敏感的地质特征，如岩石拱门，物理访问是有限的，谐振频率，模态和阻尼比的特性可能是具有挑战性的。使用稀疏的环境振动测量，我们描述了三个共振模式之间的1和40赫兹的17个自然拱在犹他州跨越的长度范围从3-88米。模态极化数据进行评估，结合联合收割机的现场观测与3-D数值模型。我们发现露头尺度的弹性模量从0.8到8.0 GPa不等，与成岩过程相关，并确定在所有网站的低阻尼。来自一个拱的密集阵列测量的相关性验证了简单弯曲模式和固定边界条件的预测。我们的研究结果建立了使用稀疏的环境共振测量的结构评估和监测的拱门和类似的独立的地质特征在世界各地。
The dynamic properties of freestanding rock landforms are a function of fundamental material and mechanical parameters, facilitating noninvasive vibration-based structural assessment. Characterization of resonant frequencies, mode shapes, and damping ratios, however, can be challenging at culturally sensitive geologic features, such as rock arches, where physical access is limited. Using sparse ambient vibration measurements, we describe three resonant modes between 1 and 40 Hz for 17 natural arches in Utah spanning a range of lengths from 3-88 m. Modal polarization data are evaluated to combine field observations with 3-D numerical models. We find outcrop-scale elastic moduli vary from 0.8 to 8.0 GPa, correlated with diagenetic processes and identify low damping at all sites. Correlation of dense-array measurements from one arch validates predictions of simple bending modes and fixed boundary conditions. Our results establish use of sparse ambient resonance measurements for structural assessment and monitoring of arches and similar freestanding geologic features worldwide.