Fundamental Mechanism and Practical Implications of Residual Stress in Rock

虽然岩石是一种古老的建筑材料，但它的工程行为令人惊讶地复杂，还有待完全了解，特别是它的工程行为。残余应力现象(RST)是指与材料形成有关的材料微结构内部锁定的应力分布，已在包括岩石在内的许多材料(如钢)中被发现。虽然在岩石中观察到了RST，但这一现象还没有被量化，也没有被包括在用于工程分析的岩石行为模型中。RST可能对高应力、块状岩层中的裂隙形成和开挖周围的位移具有实际意义。对于高水平的项目，如核废料的地质隔离，RST在预测开挖周围的裂缝形成方面可能具有重要的实际意义，这可能会潜在地影响污染物的运输。本研究计画将检视并量化RST现象及其对岩石力学的影响。将进行一项研究，以考察RST作为岩石基本行为成分的情况。由于直接观察微观机械机制的复杂性，将使用一种综合方法，该方法将利用仔细监测的实验室实验，并利用微观机械数值模拟进行解释。将在圆柱形钻芯试件中诱导损伤(微裂纹形成)(通常是在热载荷下)，并将监测由于释放RST而引起的响应。同样，也将监测由于在岩块样品中钻探而释放的RST，并增加热诱导损伤。为了量化RST效应，将使用复杂的三维、微观机械(基于岩石颗粒)的数值模拟来模拟实验。RST的影响将通过将观察到的实验响应与模型模拟行为进行协调来量化。这些发现将被用来开发一个岩石力学模型，其中包括以前被忽略的RST行为成分。RST在岩石工程问题中的实际意义将从两个研究部分来探讨：1.RST在地下开挖周围岩石损伤、岩心盘状和对岩石稳定性的影响方面的应用；2.RST在岩石开挖边界位移方面的应用。该研究项目的发现将对更全面地了解岩石破坏和位移的工程行为产生影响，并对采矿、土木工程和可持续能源项目中的地下开挖产生影响。这项研究计划将支持几名HQP的培训，包括一名博士、两名硕士和五名本科生，并将包括在实验室环境中的培训和先进数值建模的使用，这些都是学术界和加拿大工业所需的技能。

Although rock is an ancient building material, it is surprisingly complex with engineering behaviour that remains to be fully understood, in particular its engineering behaviour. The phenomenon of residual stress (RSt), a distribution of internally locked in stresses within a material's microstructure related to material formation, has been identified in many materials (e.g., steel) including rock. Although RSt has been observed in rock the phenomenon has not been quantified or included in rock behaviour models used for engineering analysis. RSt may have practical implications to fracture formation and displacement around excavations in highly stressed, massive rock formations. For high level projects, such as geological isolation of nuclear waste, the practical implications of RSt may be significant in predicting fracture formation around excavations, which can potentially influence contaminant transport.   This research program will examine and quantify the RSt phenomenon and its implications to rock mechanics. A study will be conducted to examine RSt as a fundamental rock behaviour component. Because of the complexity of observing the micromechanical mechanisms directly, an integrated methodology will be used that will utilize carefully monitored laboratory experiments augmented with interpretation using micromechanical numerical modelling simulations. Damage (microcrack formation) will be induced (typically with thermal loading) in cylindrical drill core specimens and the response due to the release of RSt will be monitored. Similarly, RSt release due to drilling in a rock block specimen, augmented with thermally-induced damage, will also be monitored. To quantify RSt effects, sophisticated three-dimensional, micromechanical (rock grain-based) numerical modelling will be used to simulate the experiments. The effects of RSt will be quantified through reconciliation of observed experiment response with model simulated behaviour. The findings will be used to develop a rock mechanics model that includes the previously disregarded RSt behaviour component. The practical implications of RSt to rock engineering problems will then be explored in two research components: 1. The application of RSt to rock damage, core disking and implications to rock stability around underground excavations; and 2. The application of RSt to rock excavation boundary displacement. The findings of the research program will have implications in obtaining a more complete understanding of engineering behaviour of rock failure and displacement with implications to underground excavations in mining, civil engineering, and sustainable energy project.   This research program will support the training of several HQP including one doctoral, two masters and five undergraduate students, and will include training in both a laboratory environment and the use of advanced numerical modelling which are both skills needed in academia and Canadian industry.