Impact of shear induced pore pressures on the ground deformations around underground openings in weak shales

剪切引起的孔隙压力对软弱页岩地下开口周围地面变形的影响

• 批准号: RGPIN-2020-05324
• 负责人: Martin, Derek
• 金额: $ 4.52万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=717592
• 关键词: Impact; shear; induced; pore; pressures

Countries with argillaceous formations have been investigating these rocks to assess their potential for the disposal of nuclear waste. In Canada, the Nuclear Waste Management Organization (NWMO) has submitted a license application to construct a low and intermediate level nuclear waste repository at a depth of 680 m in clay rich Sedimentary rocks at the Bruce Site in Ontario, and argillaceous formations remains a possible target for used-nuclear fuel disposal. In Switzerland, Nagra has commenced an extensive site investigation program to characterise the Opalinus Clay, and in France, the Callovo-Oxfordian Formation has been selected by Andra for radioactive-waste-disposal characterisation. The nuclear waste industry demands that coupled geomechanical processes are sufficiently well understood to proceed with engineering design. In these argillaceous formations, the geomechanical processes are a function of complex rate and coupled phenomena. To validate our understanding of these coupled processes in situ, field measurements supported with extensive laboratory tests will be carried out to establish the relevant geomechanical processes applicable to repository design. In argillaceous rock, pore pressures must be measured to interpret the fundamental behaviour during the mechanical and thermal loading that will be encountered in a repository underground environment. This environment creates unique boundary conditions that have the potential to generate very large pore pressures on localized zones over large distances. Such pore pressures must be quantified and accounted for in the design of the repository. This research has three specific objectives: 1) Quantify and measure the anisotropic pore pressure response parallel and perpendicular to bedding as shearing progresses using fibre optic scale piezometers installed internally in conventional triaxial tests. 2) Simulate the repository stiffness and stress boundary conditions in a servo controlled direct shear device and quantify the pore pressure response on the shearing plane using internal fibre optic piezometers. 3) Utilize existing and new pore pressure data from a specifically designed test tunnel in the Opalinus Clay at Mont Terri, Switzerland, to re-evaluate the role of shear-induced pore pressures on the underground response. The long-term objective of this research is to establish and describe the appropriate in situ constitutive behaviour of clay shales needed for repository design. In parallel with this work will be the development of a methodology and framework for implementing a performance-based design.

拥有泥质地层的国家一直在研究这些岩石，以评估它们处理核废料的潜力。在加拿大，核废物管理组织（NWMO）已提交许可证申请，将在安大略省布鲁斯遗址的富含粘土的沉积岩中680 m深处建造一个低和中水平核废物储存库，泥质地层仍然是可能的废核燃料处置目标。在瑞士，Nagra 已开始一项广泛的现场调查计划，以表征 Opalinus 粘土；在法国，Andra 已选择 Callovo-Oxfordian 地层进行放射性废物处置表征。核废料工业要求充分了解耦合地质力学过程才能进行工程设计。在这些泥质地层中，地质力学过程是复杂速率和耦合现象的函数。为了验证我们对这些现场耦合过程的理解，将进行在广泛的实验室测试支持下的现场测量，以建立适用于处置库设计的相关地质力学过程。 在泥质岩石中，必须测量孔隙压力，以解释在储存库地下环境中遇到的机械和热载荷期间的基本行为。这种环境创造了独特的边界条件，有可能在远距离的局部区域产生非常大的孔隙压力。这种孔隙压力必须在处置库的设计中进行量化和考虑。这项研究有三个具体目标： 1) 使用传统三轴测试中安装的内部光纤压力计，量化和测量剪切过程中平行和垂直于层理的各向异性孔隙压力响应。 2）模拟伺服控制直剪装置中的存储库刚度和应力边界条件，并使用内部光纤压力计量化剪切平面上的孔隙压力响应。 3) 利用瑞士蒙特特里 Opalinus 粘土中专门设计的测试隧道中的现有和新孔隙压力数据，重新评估剪切引起的孔隙压力对地下响应的作用。这项研究的长期目标是建立和描述储存库设计所需的粘土页岩的适当原位本构行为。与这项工作并行的是开发用于实施基于性能的设计的方法和框架。