Understanding the meso-structure evolution and macro-mechanical property changes in rocks under thermo-hydro-mechanical (THM) treatment is crucial for advancing and managing deep geological projects. However, due to complex discontinuity networks in rocks, achieving an accurate characterization that quantitatively correlates the micro-macro mechanical behaviors under THM conditions remains challenging. This study introduces a groundbreaking multi-scale analysis method called the grain interface-based discrete element model (GIB-DEM) to tackle this issue. By utilizing digital imaging processing (DIP) and meso-mechanical measurements, the GIB-DEM directly determines the meso-mechanical parameters of bonds, eliminating the need for complex calibration found in traditional methods. After validating the GIB-DEM through experimental and numerical Brazilian Splitting tests, we investigate the macro- mechanical behaviors of rock under different THM conditions. Our results indicate that the increase in the tensile strength at 75 °C is attributed to the tensile strength increase of quartz grain interfaces. The development of micro-cracks on the interfaces of feldspar and feldspar-quartz accounts for the decrease in tensile strength of rock under thermal and hydraulic treatment. Overall, this pioneering research provides valuable insights for optimizing Enhanced Geothermal System (EGS) projects and effectively managing Hot Dry Rock (HDR) resources.

中文翻译：

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使用基于晶粒界面的离散元模型 (GIB-DEM) 表征岩石的热水力学行为


了解热水机械（THM）处理下岩石的细观结构演化和宏观力学性质变化对于推进和管理深层地质项目至关重要。然而，由于岩石中复杂的不连续性网络，在 THM 条件下实现定量关联微观宏观力学行为的准确表征仍然具有挑战性。本研究引入了一种突破性的多尺度分析方法，称为基于晶粒界面的离散元模型（GIB-DEM）来解决这个问题。通过利用数字成像处理 (DIP) 和细观机械测量，GIB-DEM 可以直接确定键合的细观机械参数，从而无需传统方法中的复杂校准。通过实验和巴西劈裂数值试验验证 GIB-DEM 后，我们研究了不同 THM 条件下岩石的宏观力学行为。我们的结果表明，75°C 拉伸强度的增加归因于石英晶粒界面拉伸强度的增加。长石和长石-石英界面上微裂纹的发展是岩石在热处理和水力处理下抗拉强度下降的原因。总体而言，这项开创性研究为优化增强型地热系统（EGS）项目和有效管理干热岩（HDR）资源提供了宝贵的见解。