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Time-dependent crack growth in brittle rocks and field applications to geologic hazards.

机译：脆性岩石中随时间变化的裂纹扩展以及对地质灾害的现场应用。

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摘要

The primary focus of this research is to evaluate the time-dependent crack growth in rocks using lab tests and numerical modeling and its application to geologic hazard problems. This research utilized Coconino sandstone and Columbia granite as the study materials and produced the subcritical crack growth parameters in both mode I and II loadings using the rock materials. The mode I loading test employs three different types of fracture mechanics tests: the Double Torsion (DT), the Wedge Splitting (WS), and the Double Cantilever Beam (DCB) test. Each test measured the mode I crack velocity. The DT test indirectly measured the crack velocity using the load relaxation method. The WS and DCB tests directly measured the crack velocity by monitoring using a video recording. The different mode I subcritical crack growth parameters obtained from the three tests are discussed. For the mode II loading test, this study developed a new shear fracture toughness test called the modified Punch-Through Shear (MPTS). The MPTS test conducted at different loading rates produced the mode II subcritical crack growth parameters. These fracture mechanics tests were calibrated and simulated using the distinct element method (DEM) and the finite element method (FEM). DEM analysis employed the particle flow code (PFC) to simulate the mixed mode crack growth and to match with the failure strength envelop of the triaxial compressive tests. FEM analysis employed the Phase2 program to analyze the crack tip stress distribution and the FRANC2D program to calculate the modes I and II stress intensity factors. The fracture mechanics tests and numerical modeling showed well the dependency of the mode II subcritical crack growth parameters according to confining pressure, loading rate, and the mode II fracture toughness. Finally, the UDEC modeling based on DEM is utilized in this study to forecast the long-term stability of the Coconino rock slope, as one of geologic hazards. The fracture mechanics approach is implemented in the program using the modes I and II subcritical crack growth parameters obtained from the lab tests and numerical modeling. Considering the progressive failure of rock bridges due to subcritical crack growth, the UDEC results predicted the stable condition of the Coconino rock cliff over 10,000 years. This result was validated by comparing it with the previous planar failure case.
机译：这项研究的主要重点是使用实验室测试和数值模型来评估岩石中随时间变化的裂纹扩展及其在地质灾害问题中的应用。这项研究使用Coconino砂岩和Columbia花岗岩作为研究材料，并使用岩石材料在I和II型载荷下产生了亚临界裂纹扩展参数。 I模式加载测试采用三种不同类型的断裂力学测试：双扭转（DT），楔形劈裂（WS）和双悬臂梁（DCB）测试。每种测试都测量了I型裂纹速度。 DT试验使用载荷松弛法间接测量了裂纹速度。 WS和DCB测试通过使用视频记录进行监视来直接测量裂纹速度。讨论了从这三个测试获得的不同模式I亚临界裂纹扩展参数。对于II型载荷测试，本研究开发了一种新的剪切断裂韧性测试，称为改进的打孔剪切（MPTS）。在不同的加载速率下进行的MPTS测试产生了II型亚临界裂纹扩展参数。这些断裂力学测试是使用离散元方法（DEM）和有限元方法（FEM）进行校准和模拟的。 DEM分析使用粒子流代码（PFC）来模拟混合模式的裂纹扩展，并与三轴压缩测试的破坏强度包络相匹配。有限元分析使用Phase2程序分析裂纹尖端应力分布，并使用FRANC2D程序计算模式I和II应力强度因子。断裂力学测试和数值模型很好地表明了II型亚临界裂纹扩展参数与围压，加载速率和II型断裂韧性之间的相关性。最后，本研究利用基于DEM的UDEC建模来预测作为地质灾害之一的Coconino岩质边坡的长期稳定性。在程序中使用从实验室测试和数值模型获得的I和II型亚临界裂纹扩展参数来实施断裂力学方法。考虑到亚临界裂纹的增长导致岩石桥梁的逐步破坏，UDEC的结果预测了10,000年内Coconino岩石峭壁的稳定状态。通过与以前的平面故障案例进行比较，验证了该结果。

著录项

  • 作者

    Lee, Ji Soo.;

  • 作者单位

    The University of Arizona.$bMining Geological & Geophysical Engineering.;

  • 授予单位 The University of Arizona.$bMining Geological & Geophysical Engineering.;
  • 学科 Engineering Mining.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 271 p.
  • 总页数 271
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 矿业工程;
  • 关键词

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