Committee on Geological and Geotechnical Engineering

- 我知道工程表征岩石类材料与大空隙Project摘要：虽然孔隙率对岩石强度和弹性性能的影响已被广泛研究的实验和分析，大孔隙度（大空隙）的强度和弹性性能的影响知之甚少，并在科学文献中很少解决。 除了对这些材料缺乏基本的科学理解外，研究结果对一些实体也很重要。 这项研究的最重要的方面之一是它的适用性的分析和设计的美国高水平放射性核废物处置库;部分处置库将建造在凝灰岩单位，包含大腔。 这项研究也将与弱胶结骨料的工程应用有关，弱胶结骨料目前被用作矿井开口的回填和天坑的稳定，并可能作为潜在的抗冲击材料用于军事或国土安全。这项研究的主要目的是研究显示大孔隙的材料的工程行为，通过量化作为大孔隙度特性的函数的行为变化。 一个三阶段的方法将采用，对应于四个研究生的硕士论文工作。 在研究的第一和第二阶段，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、粘聚力）、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。 第三阶段将集中研究多种尺寸的空腔的影响，因为真实的大孔材料往往包含各种尺寸的空腔。 建议项目的所有阶段将通过实验室测试和数值模拟相结合的方式完成，利用蒙大拿理工大学最先进的岩石三轴测试仪器和PFC 3D离散元数值模拟软件。将测试真实的岩石（凝灰岩）和胶结堆石试样以及由含有聚苯乙烯泡沫塑料夹杂物的巴黎石膏组成的合成试样。 在使用实验数据进行验证后，数值模型将用于补充实验室实验数据，以便在更广泛的条件下分析更多样本。拟议的项目团队是跨学科和跨院校的，包括来自三个不同部门的教师（土木，地质和采矿工程）在两个校区（蒙大拿大学蒙大拿理工学院和北佛罗里达大学，都主要是本科院校）。 为为期3天的关于伊塔斯卡PFC软件的短期课程提供资金，将使项目参与者以及应邀参加的工程界其他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上的演讲传播，并将纳入蒙大拿理工学院的几门课程。 该项目最令人兴奋和最有益的方面之一是提供广泛的合作机会，允许共享工具，想法和专业知识。这项工作将通过为女性PI和几名女性研究生提供支持，促进工程人员队伍的多样性。 本科生和高中生将参与工作的各个方面;这些学生和研究生研究人员之间的互动预计将鼓励年轻学生继续他们的教育到一个新的水平。

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.