Exploring thermo-hydro-mechanical-chemical (THMC) coupled processes during swelling of clay-sulfate rocks

探索粘土硫酸盐岩石膨胀过程中的热-水-机械-化学（THMC）耦合过程

• 批准号: 530391639
• 负责人: Professor Dr. Christoph Butscher
• 金额: --
• 依托单位: Institut für Geotechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/530391639?language=en
• 关键词: Exploring; thermo; hydro; mechanical; chemical

Despite the importance in geotechnical applications and geological processes, the swelling of rocks is still insufficiently understood, while its effects at the scale of engineering projects are significant. This joint research will bring together the experimental and modeling skills of French and German partners to characterize, understand and model the macroscopic effects of rock swelling from microscale processes. The planned research will focus on clay-sulfate rocks, where clay swelling and chemical swelling occur together and influence each other. The overarching goal of the proposed research is to generate experimental results that quantitatively characterize the thermal, hydraulic, mechanical and chemical (THMC) coupled swelling behavior of rocks, and translate the results into constitutive equations for numerical simulations. The research plan is structured into four tasks. The first three tasks are experimental and will be used to inform the models developed in Task 4. Task 1 includes the preparation and characterization of the samples. Both mineralogical analysis (X-ray diffraction, Rietveld method, thin section analysis) and chemical analysis (X-ray fluorescence spectrometry) will be performed. Fluid samples taken during the swelling experiments will also be analyzed (microwave plasma atomic emission spectrometry, titration). We will perform flow-through swelling experiments in Task 2 to observe how samples swell and how their permeability evolves during swelling. To understand and interpret the macroscopic swelling behavior observed in Task 2, advanced imaging of the samples at a smaller scale will be performed in Task 3. We will use X-ray computed microtomography (XRCT) and magnetic resonance imaging (MRI) to make direct observations of pore structure and fluid flow, and their changes during swelling. Moreover, chemical reactions can be tracked in space and time contemporaneous with swelling by observing changes in pore space, density and water content. These experiments will be complemented by scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and NMR cryoporometry. The results will enable us to tell where and when both fluid flow (e.g., rock matrix versus discontinuities) and chemical swelling (location and time of conversion) occur, and how they are related to mechanical (e.g., density/volume) and hydraulic (e.g., porosity, flow rate) parameters. Data gathered in Tasks 1 to 3 will be the basis for model development, calibration, and validation in Task 4. THMC constitutive laws will be deduced based on the data obtained in Tasks 2 and 3, and predicted by Fast Fourier Transform from the microstructural observations performed in Task 3. The constitutive laws will be implemented in two open-source THMC-coupled finite elements codes (Bil and OpenGeoSys) and validated on the experiments. The two numerical approaches will be compared with each other.

尽管在岩土工程应用和地质过程中的重要性，岩石的膨胀仍然没有得到充分的理解，而其在工程项目的规模的影响是显着的。这项联合研究将汇集法国和德国合作伙伴的实验和建模技能，以表征，理解和模拟岩石膨胀的宏观效应。计划的研究将集中在粘土-硫酸盐岩，其中粘土膨胀和化学膨胀同时发生并相互影响。所提出的研究的总体目标是产生实验结果，定量表征热，水力，机械和化学（THMC）耦合的岩石膨胀行为，并将结果转化为数值模拟的本构方程。研究计划分为四个任务。前三个任务是实验性的，将用于为任务4中开发的模型提供信息。任务1包括样品的制备和表征。将进行矿物学分析（X射线衍射、Rietveld法、薄片分析）和化学分析（X射线荧光光谱法）。还将分析溶胀实验期间采集的液体样品（微波等离子体原子发射光谱法、滴定法）。我们将在任务2中进行流通溶胀实验，以观察样品如何溶胀以及溶胀期间其渗透性如何演变。为了理解和解释任务2中观察到的宏观溶胀行为，将在任务3中以较小规模对样品进行高级成像。我们将使用X射线计算机断层扫描（XRCT）和磁共振成像（MRI），使孔结构和流体流动，以及它们在膨胀过程中的变化的直接观察。此外，通过观察孔隙空间、密度和含水量的变化，可以在膨胀的同时在空间和时间上跟踪化学反应。这些实验将补充扫描电子显微镜（SEM），压汞孔隙率（MIP）和NMR cryoporometry。结果将使我们能够告诉在哪里和何时两种流体流动（例如，岩石基质与不连续性）和化学膨胀（转换的位置和时间）发生，以及它们如何与机械（例如，密度/体积）和水力（例如，孔隙率、流速）参数。任务1至3中收集的数据将作为任务4中模型开发、校准和验证的基础。THMC本构关系将根据任务2和任务3中获得的数据推导，并通过任务3中进行的微观结构观察进行快速傅立叶变换预测。本构关系将在两个开源THMC耦合有限元代码（Bil和OpenGeoSys）中实现，并在实验中进行验证。这两种数值方法将相互比较。