Ultrasonic and Acoustic Emission Imaging of Brittle Fracturing Processes to Investigate the Progressive Failure of Rock

*加拿大正面临新一代工程挑战，涉及深层地下挖掘和资源开采。几个矿山正在接近3000米深，导致开挖经历了严重的应力诱导的脆性破坏和岩石破裂危险。这对地雷设计有重大影响，包括安全和有效的支持。加拿大的核废料管理计划现在正在寻找一个具有满足安全要求所需的地质条件的深层储存库的地点。评估应力引起的脆性破裂的可能性是至关重要的，因为由此产生的开挖损伤区可能会使充当地质屏障的岩石的渗透性增加2到3个数量级。水力压裂作业使加拿大的非常规气藏能够生产，一直受到公众、行业和监管机构对诱发地震活动的担忧。由于我们在理解断层滑动机制以及控制事件可能性和震级分布的因素方面存在知识差距，人们的担忧日益加剧。本提案所要求的实验设备将帮助我们加快应对这些挑战的研究计划，使我们能够成像并因此提高我们对脆性破裂过程的理解，以及测量和量化它们对岩石强度、变形和渗透率变化的影响的能力。*所需的设备将利用现有的最先进的岩石测试设施，能够模拟地球深处经历的高应力、孔压和温度，同时测量岩石应力、应变和渗透率的变化。为此，所要求的设备将增加独特的能力，以检测和成像脆性断裂损伤的开始及其通过渐进式岩石破坏的演变。具体地说，这包括同时进行脆性断裂损伤各向异性和故障定位的时移超声速度成像，以及利用声发射(AE)检测脆性断裂的震源位置和震源机制。我们在实验岩石力学方面有良好的记录，我们能够将实验结果与基于现场的观察、最先进的数值模拟和新的4-D全息可视化相结合，这一点得到了放大。这种协同效应导致了改进的实验设计和对结果的更稳健的解释。我们已经就这些主题发表了广泛的文章，所需的设备将使我们能够继续发展我们以前的研究成果。另外，这些设备还将创造许多跨学科合作的机会，让同事们研究与二氧化碳封存、地热能以及地震、滑坡和火山灾害有关的脆性破裂过程的作用和演变。

***Canada is facing a new generation of engineering challenges involving deep underground excavations and resource extraction. Several mines are approaching 3000 m depth resulting in excavations experiencing significant stress-induced brittle failure and rock bursting hazards. This has significant implications for mine designs, including safe and effective support. Canada's nuclear waste management program is now searching for a site for a deep repository with the geological conditions necessary to satisfy safety requirements. Assessing the potential for stress-induced brittle fracturing is essential for this as the resulting excavation damage zone may increase the permeability of the rock acting as a geological barrier by 2 or 3 orders of magnitude. Hydraulic fracturing operations to enable production from Canada's unconventional gas reservoirs have been subject to public, industry, and regulator concerns regarding induced seismicity. Growing concerns are heightened due to knowledge gaps in our understanding of fault slip mechanisms and the factors controlling the likelihood and magnitude distribution of events. The experimental equipment being requested in this proposal will help us to accelerate our research programs addressing these challenges, by allowing us to image and therefore improve our understanding of brittle fracture processes and ability to measure and quantify their effects on rock strength, deformation and permeability change. ******The equipment requested will leverage an existing state-of-the-art rock testing facility capable of simulating the high stresses, pore pressures and temperatures experienced deep within the Earth, while measuring rock stress, strain, and permeability change. To this, the requested equipment will add unique capabilities to detect and image the initiation of brittle fracture damage and its evolution through progressive rock failure. Specifically, this includes simultaneously conducting time-lapse ultrasonic velocity imaging of brittle fracture damage anisotropy and failure localization, as well as detecting the source locations and source mechanisms of the brittle fractures generated using acoustic emissions (AE). We have a proven track record in experimental rock mechanics that is amplified by our ability to integrate experimental results with field-based observations, state-of-the-art numerical modelling, and new 4-D holographic visualization. This synergy leads to both improved experimental design and more robust interpretation of results. We have published extensively on these topics, and the requested equipment will allow us to continue to build upon our previous research successes. Separately, the equipment will also create numerous opportunities for interdisciplinary collaboration involving colleagues studying the role and evolution of brittle fracture processes related to CO2 sequestration, geothermal energy, and earthquake, landslide and volcano hazards.**