Use of Seismic Resonance Measurements to Determine the Elastic Modulus of Freestanding Rock Masses
Use of Seismic Resonance Measurements to Determine the Elastic Modulus of Freestanding Rock Masses
复制标题
使用地震共振测量来确定独立岩体的弹性模量
DOI：
10.1007/s00603-018-1554-6
复制
发表时间：
2018
影响因子：
6.2
通讯作者：
M. Thorne
中科院分区：
文献类型：
--
作者：
J. Moore;Paul R. Geimer;R. Finnegan;M. Thorne
测量数十米尺度的原位岩体弹性模量仍然是实验岩石力学的一个重要挑战。在这里，我们提出了一种新方法，使用独立岩石地貌的环境共振测量来识别振动模式，然后将其与实现批量、全球代表性材料属性的 3D 数值模型相匹配。结果是通过实验确定（尽管经过数值校准）的岩体弹性模量的估计值。我们在犹他州南部的五个天然岩拱上演示了该方法，每个岩拱均形成于纳瓦霍砂岩中，我们在那里获取了共振数据，并使用 3D 数值模态分析匹配了实验共振模式。可以改变两种材料特性以匹配实验数据：密度和模量。我们保持密度常数，应用测量值或参考值，并使用正向方法求解弹性模量。解析的模量代表了整体小应变动态行为，在特征尺度上整合了岩体非均质性。该技术适用于表现出清晰振动模式的独立地质地貌。不确定的机械边界条件或强烈的材料各向异性会产生误差。解析的模量值添加了描述从实验室样本到原位岩体的弹性特性随尺度变化的相关信息。
Measuring the elastic modulus of in situ rock masses over scales of tens of meters remains an important challenge in experimental rock mechanics. Here we present a new approach using ambient resonance measurements of freestanding rock landforms to identify vibrational modes, which are then matched with 3D numerical models implementing bulk, globally representative material properties. The result is an experimentally determined, albeit numerically calibrated, estimate of rock mass elastic modulus. We demonstrate the approach at five natural rock arches in southern Utah, each formed in Navajo Sandstone, where we have acquired resonance data and matched experimental resonant modes using 3D numerical modal analysis. Two material properties can be varied to match experimental data: density and modulus. We hold density constant, applying measured or reference values, and solve for elastic modulus using a forward approach. The resolved modulus is representative of the global small-strain dynamic behavior, integrating rock mass heterogeneity over the scale of the feature. The technique works well for freestanding geological landforms that exhibit clear vibrational modes. Errors arise with uncertain mechanical boundary conditions or strong material anisotropy. The resolved modulus values add relevant information describing the variation of elastic properties over scales from lab samples to in situ rock masses.