From micro- to macro-scale characterization of geomaterials: the role of heterogeneities and scale in geomechanics

从微观到宏观尺度表征岩土材料：非均质性和尺度在地质力学中的作用

• 批准号: RGPIN-2019-07146
• 负责人: Grasselli, Giovanni
• 金额: $ 5.32万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749348
• 关键词: micro; macro; scale; characterization; geomaterials

Mechanical and geometrical properties of rock at grain (micro-) scale govern the behaviour of rock-masses at all scales. In recent years, my research group, among others, has developed and successfully used micro-mechanical hybrid finite/discrete element modeling techniques (FDEM) to simulate tunneling and other underground engineering activities. These results support the hypothesis that physically-based calibrated micro-mechanical models can inherently capture the heterogeneity and the scale effect observed in all geomaterials, and reproduce, as emergent behaviours, those underlying physical processes associated with complex failure mechanisms in rock (i.e., spalling, fracking, progressive slope instabilities). However, to date, no accepted procedure exists on how to relate micro-scale input parameters to specific lab measured values; thus, researchers have difficulties when it comes to soundly calibrating and verifying their models. Long-term goal of my research program: to understand the role that heterogeneities have, at all scales, on the behaviour of engineering and geological structures (i.e., tunnels, mines, reservoirs) subjected to varying multi-physics (Thermo-Hydro-Mechanical-Chemical) conditions, and to translate it into numerical solutions. Short-term objectives Obj.1 Understanding how spatial, volumetric, and scale distributions of heterogeneities influence localization and progression of deformational and failure processes. Obj.2 Development of a general methodology for the quantitative validation and calibration of micromechanical numerical codes. Obj.3 Development of a reproducible and reliable strategy for upscaling the use of micromechanical numerical codes to study rock behaviour at various spatial resolutions, from laboratory to tunnel/mine/reservoir scale. The validation process will evaluate the micro-scale physics implemented in the numerical codes and their ability to reproduce, as an emergent property of the model, macro-scale behaviours observed both in the laboratory and in the field. The novelty of this research program is the unique combination of advanced micromechanical laboratory investigations, empirical and machine learning analysis, and micromechanical FDEM modeling, to address a very old, but still unsolved problem in geomechanics: the scale effect. The anticipated outcome of this research will greatly contribute to reduce the scale-related uncertainties inherent to most geomechanical engineering projects (e.g., excavation of deep geological nuclear waste repositories, tunnels, mines, energy exploitation activities for shale oil and gas reservoirs), as well as increase confidence in rock engineering design. The research program offers a unique opportunity for HQP training in experimental and numerical geomechanics, a subject of great interest to the whole Canadian natural resource industry.

岩石在颗粒（微）尺度上的力学和几何特性支配着所有尺度上岩体的行为。近年来，我的研究小组开发并成功地使用微力学混合有限/离散单元建模技术（FDEM）来模拟隧道和其他地下工程活动。这些结果支持了一个假设，即基于物理的校准微观力学模型可以固有地捕捉到在所有地质材料中观察到的非均质性和尺度效应，并将与岩石中复杂破坏机制相关的潜在物理过程（即剥落、破裂、渐进边坡不稳定）作为紧急行为再现。然而，迄今为止，关于如何将微尺度输入参数与特定实验室测量值联系起来，还没有公认的程序；因此，当涉及到合理校准和验证他们的模型时，研究人员有困难。我的研究计划的长期目标是：了解非均质性在各种尺度上对工程和地质结构（即隧道、矿山、水库）在不同多物理（热-水-机械-化学）条件下的行为所起的作用，并将其转化为数值解。ob1 .了解非均质性的空间、体积和尺度分布如何影响变形和破坏过程的局部化和进展。ob2 .开发微力学数值代码定量验证和校准的通用方法。Obj.3开发一种可重复和可靠的策略，以扩大微力学数值代码的使用，以研究从实验室到隧道/矿山/水库尺度的各种空间分辨率下的岩石行为。验证过程将评估在数字代码中实现的微观尺度物理，以及它们作为模型的紧急属性再现在实验室和现场观察到的宏观尺度行为的能力。该研究项目的新颖之处在于将先进的微力学实验室研究、经验和机器学习分析以及微力学FDEM建模独特地结合起来，以解决地质力学中一个非常古老但仍未解决的问题：尺度效应。本研究的预期结果将大大有助于减少大多数地质力学工程项目（例如，深层地质核废料库的挖掘、隧道、矿山、页岩油气储层的能源开采活动）固有的与规模相关的不确定性，并增加对岩石工程设计的信心。该研究项目为HQP在实验和数值地质力学方面的培训提供了一个独特的机会，这是整个加拿大自然资源行业非常感兴趣的主题。