CAREER: Stress Redistribution Imaging for Rock Failure Prediction

机构：弗吉尼亚理工学院和州立大学标题：“职业：应力重分布成像用于岩石破坏预测”这个教师早期职业发展（CAREER）研究和教育项目使用高分辨率，三维层析成像来更好地理解和交流岩石破坏过程。实现预测岩体破坏的最终目标，将大大减少死亡人数，降低施工成本，提高环境保护。破坏预测扩展到岩石力学的各个方面，包括隧道，矿山，岩石边坡，地震，废物储存库，桥梁和坝肩。为了预测岩石的破坏，监测岩石内部应力的重新分布是很有帮助的。最近计算能力的进步使得利用声波和层析成像可以做到这一点。监测应力重分布的基本原理是，在增加载荷的情况下，岩石内的微裂缝会闭合，从而使声波以更快的速度传播，衰减更小。该方法已在实验室中成功使用，并已在现场应用，但缺乏基础。本项目将为岩石应力重分布成像技术奠定坚实的理论和实践基础，1)规范方法，2)将前人的研究成果扩展到实验室和现场研究之间的差距。还将加强与岩石破坏预测有关的教育工作。与教育和研究相关的具体任务包括：1)生成三维层析图像，以观察岩石样品加载破坏时结构的相关变化；2)使用这些图像校准数值模拟结果。通过在岩石样品加载过程中收集数据，制作延时动画，帮助大学生了解应力分析。额外的教育工作集中在从呈现教学方法过渡到建构主义模型的两门本科课程，并开发一门研究生水平的课程，通过对成像和数值模拟结果的耦合分析来理解失败。

CMS-0134034PI: Erik WestmanInstitution: Virginia Polytechnic Institute and State UniversityTitle: "CAREER: Stress Redistribution Imaging for Rock Failure Prediction"This Faculty Early Career Development (CAREER) research and education project uses high-resolution, three-dimensional tomographic imaging to better understand and communicate the process of failure in rock. Accomplishing the ultimate goal of predicting rock mass failure will result in significantly reduced fatalities, lowered construction costs, and increased environmental protection. Failure prediction extends to all aspects of rock mechanics including tunnels, mines, rock slopes, earthquakes, waste repositories, and bridge and dam abutments. To predict rock failure, it is quite helpful to monitor the redistribution of stresses within the rock. Recent advances in computational power have allowed this to be done using acoustic waves and tomographic imaging. The basic principal behind monitoring the redistribution of stresses is that microfractures within the rock are closed under increased loading, allowing the acoustic wave to travel at a greater velocity and with less attenuation. This method has been used successfully in the laboratory and has had growing, but poorly founded, application in the field. This project will put the technique of imaging stress redistribution in rock on a sound theoretical and practical foundation by 1) standardizing methods and 2) extending results of prior studies into the gap between laboratory- and field-scale studies. Educational efforts related to rock failure prediction will also be enhanced.Specific tasks associated with both education and research include 1) generating three-dimensional tomographic images to observe relevant alterations to the fabric of rock samples loaded to failure, and 2) using those images to calibrate numerical modeling results. By collecting data as rock samples are loaded, time-lapse animations will be developed which will assist in the communication of stress-analysis to undergraduates. Additional educational efforts focus on transitioning from a presentational teaching method to a constructivist model for two of the proposer's undergraduate courses and developing a graduate-level course for understanding failure through coupled analysis of imaging and numerical modeling results.