Large-Scale Solute Transport in Fracture Networks

裂缝网络中的大规模溶质输运

• 批准号: RGPIN-2016-05060
• 负责人: Novakowski, Kent
• 金额: $ 4.37万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=661059
• 关键词: Large; Scale; Solute; Transport; Fracture

Contaminants emanating from industrial and waste sites in bedrock aquifers typically migrate rapidly and widely due to the pathways provided by discrete fractures and fracture interconnections. Transport processes include the tortuosity of pathways within individual fractures, the variability of matrix porosity, the variability of fracture interconnections,*lateral migration through preferential pathways, temporal effects in the hydraulic gradients,*and the dispersive effects that occur at fracture intersections.*In the proposed study we will assemble several data sets from existing well characterized*sites and the limited number of tracer experiments conducted*at large scale to provide a basis to investigate through numerical analysis the dominant transport mechanisms. Initial studies will*focus on the processes which occur in discrete fractures, and the complexity of pathways developed through the variability in fracture aperture, and the effects due to matrix diffusion are expected to dominate. In the full fracture network study, numerical analysis will again be used to evaluate the principal transport mechanisms. In this case, the dominant mechanism is expected to be the complexity of the fracture interconnections, and the dispersive effects due to the fracture intersections. Between the discrete*fracture study and the full-network analysis, two Masters students will be required. The analysis of the network experiment poses a very significant*challenge computationally and a significant component of the research will be conducted in comparing Eulerian (spatially fixed frame of reference) and Lagrangian (frame of reference which moves with the fluid) approaches for this setting that will require the fulltime*effort of one PhD*student. The comparison will be conducted at both local scale (150 m).*In order to support the numerical studies, local-scale*investigations of discrete fractures and fracture intersections will be conducted in a*crystalline rock field setting. The Applicant has developed a unique state-of-the art field site with eight boreholes drilled in an area of*approximately 20 by 30 m, in a granite gneiss. Preliminary hydraulic testing results have shown several wells which are connected by one*or more fractures, some with intersections. Tracer experiments using both solute and solute and heat will be conducted between these wells to specifically explore the dispersive effects played by fracture aperture heterogeneity and fracture intersections. This component of the study will involve two PhD students and one Masters student.*The outcome of this research will provide an assessment of the*fundamental processes governing contaminant migration in fractures, and will have practical application by hydrogeologists and engineers in the prediction of risk from waste facilities, and the management of contaminated sites in these settings.

由于离散断裂和断裂相互连接提供的路径，来自基岩含水层中工业和废物场的污染物通常会迅速而广泛地迁移。 输运过程包括单个裂缝内通道的弯曲度、基质孔隙度的可变性、裂缝互连的可变性、* 通过优先通道的侧向迁移、水力梯度的时间效应 * 以及裂缝交叉处发生的分散效应。在拟议的研究中，我们将收集几个数据集，从现有的良好表征 * 网站和数量有限的示踪剂实验进行 * 在大规模提供一个基础，通过数值分析调查的主要运输机制。最初的研究将 * 集中在离散裂缝中发生的过程，以及通过裂缝孔径的可变性开发的路径的复杂性，以及由于基质扩散的影响预计将占主导地位。在完整的裂隙网络研究中，数值分析将再次用于评估主要的输运机制。在这种情况下，预计主要机制是裂缝互连的复杂性，以及由于裂缝相交而产生的分散效应。在离散断裂研究和全网络分析之间，需要两名硕士生。网络实验的分析在计算上提出了一个非常重大的挑战，研究的一个重要组成部分将在比较欧拉（空间固定的参考系）和拉格朗日（与流体一起移动的参考系）方法中进行，这将需要一名博士生的全职努力。将在两个局部尺度（150 m）上进行比较。*为了支持数值研究，将在结晶岩场环境中对离散裂缝和裂缝交叉点进行局部尺度调查。申请人开发了一个独特的最先进的现场，在花岗岩片麻岩中约20 × 30 m的区域内钻了8个钻孔。初步水力测试结果显示，有几口威尔斯井被一条或多条裂缝连接，其中一些井有交叉点。将在这些威尔斯井之间进行使用溶质和溶质以及热量的示踪剂实验，以专门探索裂缝孔径非均质性和裂缝交叉点所发挥的分散效应。这项研究的这一部分将涉及两名博士生和一名硕士生。这项研究的结果将提供一个评估的 * 基本过程中的裂缝污染物迁移，并将有实际应用的水文地质学家和工程师在预测的风险，从废物设施，并在这些设置污染场地的管理。