Key Takeaways & Executive Findings
- •• Increased biotite content reduces uniaxial compressive strength and elastic modulus while enhancing plastic deformation and shear crack proportion. • Dynamic multifractal parameter Dam exhibits biotite-dependent segmented evolution, with oscillations in elastic phase indicating shear crack initiation and attenuation in plastic phase reflecting frictional closure. • AE-based damage models and time-varying signals effectively characterize rock damage progression, with stress concentrations around biotite fostering localized shear failure at lower damage levels. • Higher biotite content accelerates crack propagation and lowers fracture energy threshold due to smooth cleavage planes, reducing strength and stiffness.
Abstract
Biotite content critically influences rock mechanical behavior and threatens underground engineering stability. Uniaxial compression tests with acoustic emission (AE) monitoring were conducted on granite pegmatite samples having varying biotite content. Peak frequency distribution analysis, rise angle-average frequency (RA-AF) analysis, multifractal theory, and a dynamic multifractal algorithm were applied to explore the relationship between damage evolution and AE characteristics. Results indicate that increased biotite content reduces uniaxial compressive strength and elastic modulus, enhances plastic deformation, and increases the proportion of shear cracks. The segmented evolution of the dynamic multifractal parameter Dam is biotite-dependent. Oscillations during the elastic phase signify localized shear crack initiation and propagation; their attenuation in the plastic phase reflects frictional closure along biotite cleavage planes, promoting elastic energy storage and delaying release. AE-based damage models and time-varying signals characterize rock damage progression. Stress concentrations around biotite minerals foster localized shear band formation, leading to concentrated shear failure at lower damage levels. Higher biotite content accelerates crack propagation, while smooth cleavage planes lower the fracture energy threshold, reducing strength and stiffness. These findings enhance understanding of biotite-influenced progressive rock damage and underpin stability monitoring and early-warning systems for underground engineering.
1. Introduction
Granite pegmatite veins are widely distributed, large in scale, characterized by high strength, strong weathering resistance, and low permeability [1]. They are commonly employed in major underground engineering projects, including dam foundations, tunnel linings, and foundations for nuclear waste disposal facilities [2]. For instance, the nuclear waste disposal facility on Olkiluoto Island, Finland, is constructed on a granite pegmatite vein. However, as a typical intrusive rock, granite pegmatite is affected by multiple factors, including magma differentiation, thermobaric conditions, fluid activity, and late-stage alterations, leading to variations in mineral composition, particularly in biotite content [3].
Variations in biotite content significantly affect the mechanical properties and damage evolution of granite pegmatite under loading conditions, thereby posing risks to the safety and reliability of engineering structures [4]. Therefore, understanding the mechanical properties and damage evolution mechanisms of rocks affected by biotite content is essential for evaluating the long-term stability of rock masses and mitigating potential risks in underground engineering [5].
Rock strength is closely associated with its mineral composition. In analyzing the influence of mineral composition on the mechanical properties of rocks, particular attention is given to biotite content. As early as the 1990s, Shea and Kronenberg [6] performed compression tests on schist and gneiss containing 15% to 75% biotite. The results demonstrated that with increasing biotite content, the ductility of the samples increased, whereas their strength decreased. Subsequent studies have confirmed that most mechanical parameters related to rock strength, including uniaxial compressive strength, elastic modulus, and tensile strength, decrease with increasing biotite content.
Loading authentic research manuscript (Pages 1–5)...
Shuowei Liu, Jianjun Zhao, Bin Shi, Qiyi Lai, Qingmiao Li, Jianxian He, Xiao Zhao, Jie Deng, Xuejin Ying (2025). Dynamic multifractal characteristics and damage evolution of granite pegmatite with varying biotite content based on acoustic emission monitoring. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.09.012
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
How does biotite content affect the mechanical properties of granite pegmatite?
Increased biotite content reduces uniaxial compressive strength and elastic modulus, enhances plastic deformation, and increases the proportion of shear cracks, as demonstrated in the study.
What is the role of acoustic emission monitoring in this research?
Acoustic emission monitoring was used to capture real-time signals during uniaxial compression tests, enabling analysis of peak frequency distribution, RA-AF characteristics, and dynamic multifractal parameters to understand damage evolution.
What is the dynamic multifractal parameter Dam and its significance?
Dam is a dynamic multifractal parameter that exhibits segmented evolution dependent on biotite content. Oscillations during the elastic phase indicate localized shear crack initiation, while attenuation in the plastic phase reflects frictional closure along biotite cleavage planes, affecting energy storage and release.
How does biotite content influence crack propagation and failure mechanisms?
Higher biotite content accelerates crack propagation and lowers the fracture energy threshold due to smooth cleavage planes, leading to concentrated shear failure at lower damage levels and reduced strength and stiffness.
What are the practical implications of this research for underground engineering?
The findings enhance understanding of biotite-influenced progressive rock damage, supporting stability monitoring and early-warning systems for underground engineering projects such as dam foundations, tunnel linings, and nuclear waste disposal facilities.
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.