Committee on Geological and Geotechnical Engineering

摘要：虽然孔隙度对岩石强度和弹性性能的影响已经得到了广泛的实验和分析研究，但宏观孔隙度（大空隙）对岩石强度和弹性性能的影响却知之甚少，科学文献中也很少提及。除了基本缺乏对这些材料的科学理解之外，这些结果对许多实体都很重要。本研究最重要的一个方面是其对美国高放射性核废料处置库分析和设计的适用性；储存库的一部分将在凝灰岩单元中建造，其中包含大的空腔。该研究还将与涉及弱胶结骨料的工程应用相关，这些骨料目前被用作矿山开口的回填材料和沉坑的稳定，并可能作为潜在的抗冲击材料用于军事或国土安全。本研究的主要目的是通过量化行为变化作为宏观孔隙度特征的函数来研究具有宏观孔隙度的材料的工程行为。将采用三个阶段的方法，对应于四个研究生的硕士论文工作。在第一和第二阶段的研究中，将量化空腔尺寸和空腔形状对强度（无侧限抗压强度、摩擦角、黏聚力）、变形能力（杨氏模量）和破坏行为（应力-应变响应和破坏模式）的影响。第三阶段将重点研究多种空腔尺寸的影响，因为真正的大孔材料往往包含广泛的空腔尺寸。拟议项目的所有阶段将通过实验室测试和数值模拟的结合来完成，利用蒙大拿理工大学最先进的岩石三轴测试仪器和PFC3D不同元素数值模拟软件。将测试真实的岩石（凝灰岩）和胶结的填石标本，以及由含有泡沫聚苯乙烯内含物的巴黎石膏组成的合成样品。在使用实验数据进行验证后，将使用数值模型来补充实验室实验数据，以便在更广泛的条件下分析更多的样品。拟议的项目团队是跨学科和跨机构的，包括来自两个校区（蒙大拿大学的蒙大拿理工学院和北佛罗里达大学，两个主要的本科机构）三个不同部门（土木、地质和采矿工程）的教师。资助为期3天的Itasca PFC软件短期课程将使项目参与者以及其他将被邀请参加的工程界感兴趣的成员能够更深入地了解这一强大的数字工具。研究结果将通过期刊出版物和岩石力学研讨会进行传播，并将被纳入蒙大拿理工学院的几门课程中。广泛的合作机会，将允许分享工具，想法和专业知识，是该项目最令人兴奋和有益的方面之一。这项工作将通过为一名女PI和几名女研究生提供支持，促进工程人员的多样性。本科生和高中生将参与到各方面的工作中；这些学生和研究生研究人员之间的互动有望鼓励年轻的学生继续他们的教育到下一个水平。

RUI: Engineering Characterization of Rock-Like Materials with Large VoidsProject Abstract:While the effects of porosity on rock strength and elastic properties have been widely investigated both experimentally and analytically, the effects of macroporosity (large voids) on strength and elastic properties are poorly understood and are poorly addressed in the scientific literature. Besides the basic lack of scientific understanding of these materials, the results are of importance to a number of entities. One of the most important aspects of this study is its applicability to the analysis and design of the U.S. high level radioactive nuclear waste repository; portions of the repository will be constructed in tuff units that contain large cavities. The research will also be relevant to engineering applications involving weakly cemented aggregates, which are currently employed as backfill for mine openings and stabilization of sinkholes, and may possibly have military or homeland security uses as potential impact-resistant materials.The primary aim of this research is to investigate the engineering behavior of materials displaying macroporosity, by quantifying the variation in behavior as a function of macroporosity characteristics. A three stage approach will be employed, corresponding to master's thesis work of four graduate students. In the first and second stages of the research, the effects of cavity size and cavity shape, on the strength (unconfined compressive strength, friction angle, cohesion), deformability (Young's modulus), and failure behavior (stress-strain response and failure mode) will be quantified. The third stage will focus on studying the effects of multiple sizes of cavities, since real macroporous materials tend to contain a wide range of cavity sizes. All stages of the proposed project will be accomplished through a combination of laboratory testing and numerical modeling, utilizing Montana Tech's state-of-the-art rock triaxial testing apparatus and PFC3D distinct element numerical modeling software.Real rock (tuff) and cemented rockfill specimens as well as synthetic samples composed of plaster of Paris with Styrofoam inclusions will be tested. After performing validation using the experimental data, numerical models will be used to supplement the laboratory experimental data, facilitating analysis of a larger number of samples under a wider range of conditions.The proposed project team is both interdisciplinary and inter-institutional, involving faculty from three different departments (Civil, Geological, and Mining Engineering) on two campuses (Montana Tech of The University of Montana and the University of North Florida, both primarily undergraduate institutions). Funding for a 3-day short-course on Itasca's PFC software will allow project participants, as well as other interested members of the engineering community who will be invited to attend, to gain a more thorough understanding of this powerful numerical tool. The research results will be disseminated via journal publications and presentation at rock mechanics symposia, and will be incorporated into several courses at Montana Tech. The extensive opportunity for collaboration, which will allow sharing of tools, ideas, and expertise, is one of the most exciting and beneficial aspects of the project.The work will promote diversity within the engineering workforce by providing support for a female PI and several female graduate students. Undergraduate and high school students will be involved in various aspects of the work; interaction between these students and the graduate student researchers is expected to encourage the younger students to continue their education to the next level.