Mechanical and Geophysical Characterization of Damage in Anisotropic Rock

各向异性岩石损伤的机械和地球物理特征

• 批准号: 0856296
• 负责人: Antonio Bobet
• 金额: $ 41.19万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0856296&HistoricalAwards=false
• 关键词: Mechanical; Geophysical; Characterization; Damage; Anisotropic

In rock, changes in applied stress often result in damage caused by the creation of new cracks in the intact material, initiation of new cracks from pre-existing fractures, or slip along pre-existing discontinuities. Ultimately coalescence of pre-existing and/or newly created cracks can induce failure in the rock mass. The Deep Underground Science and Engineering Laboratory (DUSEL) requires the excavation of very deep large underground cavities for the proposed physics experiments. Such excavation poses a significant engineering challenge because of the unprecedented combination of high stress and the large size of the caverns. The caverns will be excavated in the Yates formation, which opens additional questions because of the anisotropy in rock properties. The objectives of the research are to determine: fracturing mechanisms in anisotropic rock; the effect of shear cracks on fracture coalescence; and the geometrical and mechanical properties of fractures prior to and during formation using active geophysical monitoring. The results of the research will provide key understanding of fracturing for open and closed (frictional) fractures in anisotropic rock, and will support the design of experiments for DUSEL to field-test these theories. The research is multi-faceted, consisting of experimental observations and measurements at the micro- and meso-scales, and complemented with numerical simulations of the experiments. Laboratory experiments coupled with geophysical monitoring will be conducted to identify and classify the coalescence mechanisms in systems with multiple non-persistent open and closed discontinuities in anisotropic brittle rock, and are designed to determine the changes in seismic wave transmission with crack initiation, slip and coalescence. The material used for the experiments is rock from the Yates formation, i.e. the host rock where the large caverns at DUSEL will be excavated. In addition to the benefits for DUSEL, this represents much-needed research that will unify what is known of fracturing of open flaws in isotropic rocks with open and closed flaws in anisotropic rocks. Interaction of engineers and geophysicists is highly desirable and eventually must lead to the application of engineering techniques to geophysical methods and geophysical measurements to the validation of theories and methodologies. The work is particularly important for the field of rock mechanics where there is no direct access to the rock undergoing damage. Knowledge transfer from research to academia and practice is integrated into a series of modules that include all stakeholders, from K-12 to undergraduate and graduate students and to rock mechanics professionals. The educational outreach component of the project includes a site visit to DUSEL in Lead, SD. A diverse group of undergraduate students, graduate students, science teachers in local schools and the two PIs will participate.

在岩石中，施加应力的变化常常导致损伤，造成损伤的原因包括：在完整的材料中产生新的裂缝，在原有的裂缝中产生新的裂缝，或者沿着原有的不连续面滑动。最终，已存在和/或新形成的裂缝合并会导致岩体的破坏。深地下科学与工程实验室（DUSEL）需要挖掘非常深的地下大洞进行拟议的物理实验。由于前所未有的高应力和大型洞穴的结合，这种挖掘提出了重大的工程挑战。洞穴将在Yates地层中挖掘，由于岩石性质的各向异性，这带来了额外的问题。研究的目的是：确定各向异性岩石中的压裂机制；剪切裂纹对裂缝聚结的影响利用主动地球物理监测，分析了地层前和地层中裂缝的几何力学性质。研究结果将为各向异性岩石中开放和封闭（摩擦）裂缝的压裂提供关键理解，并将为DUSEL的实验设计提供支持，以对这些理论进行现场测试。该研究是多方面的，包括实验观测和微观和中尺度的测量，并辅以实验的数值模拟。通过实验室实验结合地球物理监测，对各向异性脆性岩石中具有多个非持续性开闭不连续面系统的聚结机制进行识别和分类，确定地震波传播随裂缝起裂、滑移和聚结的变化。实验所用的材料是耶茨地层的岩石，也就是将在DUSEL挖掘大型洞穴的宿主岩石。除了对DUSEL的好处之外，这代表了急需的研究，将各向同性岩石中开放缺陷的压裂与各向异性岩石中的开放缺陷和封闭缺陷统一起来。工程师和地球物理学家的相互作用是非常可取的，并且最终必须导致工程技术应用于地球物理方法和地球物理测量来验证理论和方法。这项工作对于岩石力学领域尤其重要，因为在这个领域，无法直接接近遭受破坏的岩石。从研究到学术和实践的知识转移被整合到一系列模块中，包括所有利益相关者，从K-12到本科生和研究生，再到岩石力学专业人士。该项目的教育推广部分包括对SD铅市DUSEL的实地考察。来自当地学校的本科生、研究生、科学教师和两名pi将参与其中。