Key Takeaways & Executive Findings
- •• Mineral interfaces in granite exhibit transitional mechanical properties, with elastic modulus and hardness intermediate between adjacent mineral phases. • Higher plasticity indices at interfaces indicate enhanced plastic deformation capacity of hard-phase minerals in these regions. • Fracture toughness of mineral interfaces ranges from 0.90 to 1.63 MPa m0.5, providing critical data for micromechanical modeling. • A significant positive linear correlation exists between elastic modulus and fracture toughness at the rock scale, but this correlation weakens at the mineral scale, revealing a scale effect.
Abstract
Understanding the mechanical behavior of diagenetic mineral granules and interfaces in granite provides essential experimental references for constructing micromechanical models of granite. The micromechanical behavior of Yanshanian granite is investigated using scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) and nanoindentation tests. The results demonstrate transitional mechanical properties at mineral interfaces. The elastic modulus and hardness exhibit intermediate values between adjacent mineral phases. The higher plasticity indices at the interfaces suggest higher plastic deformation capacity of hard-phase minerals in these regions. Additionally, fracture toughness measurements of minerals and interfaces were obtained, with interfacial values ranging from 0.90 to 1.63 MPa m0.5. The analysis of mechanical property relationships shows a significant positive linear correlation between rock-scale elastic modulus and fracture toughness. However, this correlation is substantially lower at the mineral scale, demonstrating a scale effect in the relationship of different mechanical properties.
1. Introduction
The depletion of fossil fuels, coupled with environmental issues, such as the greenhouse effect, rising regional acid rain, and nitrogen oxide pollution, has caused a shift toward environmentally friendly renewable energy sources [1]. Geothermal energy has become a research hotspot due to its widespread availability, cleanliness, and stability [2]. Granite is a common rock in hot dry rock (HDR) reservoirs [3]; thus, an in-depth study into granite’s mechanical characteristics is required to guide long-term geothermal energy development [4].
Traditional tests like uniaxial and triaxial compression tests are typically conducted to assess the macromechanical properties of granite and obtain inputs for numerical simulations. However, HDR reservoirs are typically located at depths exceeding 3000 m, presenting significant challenges for conventional experimental methods. Core extraction at such depths is expensive and time-consuming, with low recovery rates of intact cores due to the release of high in-situ stresses, complicating the acquisition of reservoir rock mechanics data [5]. Nanoindentation testing is a promising solution to these challenges. Unlike conventional testing approaches, nanoindentation imposes minimal constraints on sample geometry and can be performed directly on irregular rock fragments, substantially reducing the time and costs associated with core extraction and specimen preparation [6]. Furthermore, this technique exhibits exceptional testing efficiency while providing nanoscale resolution for characterizing localized features, such as the mechanical properties of mineral phases and their interfaces [7]. Therefore, nanoindentation testing has been increasingly utilized in rock mechanics over the past decades and has recently been extended to analyzing extraterrestrial rock mechanics [8,9], offering an innovative approach to characterizing mechanical properties.
Loading authentic research manuscript (Pages 1–5)...
Pengli Zhou, Cunbao Li, Heping Xie (2025). Micromechanical properties of granite with insights into mineral interface mechanics. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.08.009
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the main objective of this study?
The study aims to investigate the micromechanical properties of granite, focusing on mineral interfaces, using nanoindentation and SEM-EDS to provide experimental references for constructing micromechanical models.
How were the mechanical properties of mineral interfaces characterized?
Nanoindentation tests were performed on Yanshanian granite, and SEM-EDS was used to identify mineral phases. The elastic modulus, hardness, plasticity index, and fracture toughness were measured at mineral interfaces and compared to adjacent mineral phases.
What are the key findings regarding mineral interfaces?
Mineral interfaces exhibit transitional mechanical properties, with elastic modulus and hardness intermediate between adjacent minerals. They also show higher plasticity indices, indicating enhanced plastic deformation capacity, and fracture toughness values ranging from 0.90 to 1.63 MPa m0.5.
What is the significance of the scale effect observed?
The study found a strong positive linear correlation between elastic modulus and fracture toughness at the rock scale, but this correlation is weaker at the mineral scale, highlighting a scale effect that must be considered in upscaling micromechanical properties.
Why is nanoindentation advantageous for studying deep reservoir rocks?
Nanoindentation requires minimal sample preparation and can be performed on irregular rock fragments, reducing costs and time associated with deep core extraction. It provides nanoscale resolution to characterize localized mechanical properties, making it ideal for studying rocks from deep geothermal reservoirs.
Related Technical Papers & Translations
A Novel Approach for Enhanced Brain Tumor Segmentation Using Multimodal MRI and Deep Learning
Brain tumor segmentation from multimodal MRI is crucial for diagnosis and treatment planning. In this study, we propose a novel deep learning framework that integrates structural and functional imaging modalities to improve segmentation accuracy. Our method employs a multi-scale attention mechanism and a hybrid loss function to handle class imbalance and boundary ambiguity. Evaluated on the BraTS benchmark, our approach achieves state-of-the-art performance, with Dice scores of 0.91, 0.87, and 0.84 for whole tumor, core, and enhancing tumor, respectively. Furthermore, we demonstrate the generalizability of our model across different scanners and protocols. Our findings suggest that the proposed method can significantly aid clinical decision-making and surgical planning.
Investigation of coupled acoustic and electrical responses and early warning approaches during re-loading of damaged coal
Initial damage from engineering disturbances in deep coal mining degrades mechanical properties and heightens dynamic-hazard risks, challenging conventional monitoring. This study probes the coupled acoustic-electrical responses of initially damaged coal under reloading and develops a multi-parameter, multi-level dynamic integrated early-warning model. Using a true-triaxial Split Hopkinson Pressure Bar (SHPB) system, we prepared specimens with graded damage by varying static deviatoric stresses and dynamic impacts. Uniaxial compression reloading was conducted with synchronous acoustic emission (AE) and resistivity monitoring. Joint time-domain responses of force, acoustics, and electricity delineated distinct loading stages. Time-frequency features were extracted via Fourier and wavelet transforms; crack architecture was quantified by 3D AE localization and fractal-dimension analysis. Initial damage markedly reduced load-bearing capacity. Resistivity decreased sharply with increasing deviatoric stress, while cumulative AE counts increased strongly. The AE spectrum evolved from bimodal to broadband with low- and high-frequency enhancement. The resistivity spectrum showed progressive bandwidth broadening, energy amplification, and high-frequency advancement. The AE spatial fractal dimension rose significantly during compaction. An integrated warning system combining multiscale entropy fusion, Temporal Convolutional Network (TCN)-Transformer forecasting, recurrence-network analysis, and a Bayesian framework yielded a 28.4 s lead time, offering a theoretical basis and technical pathway for intelligent prevention of dynamic hazards.
Influence of aggregate particle size on fracture behavior and energy evolution of cemented rockfill in the post-peak stage
Cemented rockfill (CRF) combines structural support with sustainable reuse of coal-derived solid waste. This study integrates digital image correlation, acoustic emission monitoring, and finite–discrete element simulations to investigate mechanical behavior, fracture development, and energy evolution of CRF containing 54% aggregate content with three grain-size distributions (5–10, 10–20, and 20–30 mm). Results indicate finer aggregates raise compressive strength and elastic modulus, and increase post-peak softening and residual stiffness. Fracture patterns transition from dominantly unidirectional failure in coarse specimens to pronounced X-shaped conjugate shear in fine specimens, with cracks initiating at boundaries and propagating inward. The proportion of failed joints at comparable strains decreases markedly with finer gradation, reflecting a more homogeneous crack network that enhances post-peak load retention and produces frequent minor stress fluctuations. Energy analyses reveal a coarse > medium > fine ordering in cumulative dissipation; however, finer aggregates delay rapid kinetic and dissipative energy release, promoting slower energy redistribution and improved load resistance. These findings quantify how aggregate gradation controls deformational mechanisms, crack topology, and energy partitioning, and provide design guidance for optimizing aggregate size and cementitious composition to enhance ductility, energy absorption, and structural reliability of CRF in underground engineering.