Key Takeaways & Executive Findings
- •• Confining pressure linearly enhances yield and compressive strength, improving granite deformability and shifting failure from brittle to ductile. • Higher confining pressure raises microcrack initiation stress threshold and suppresses crack propagation, increasing shear crack proportion from 18.71% to 61.2%. • Confining pressure promotes grain boundary shear cracks (GBSCs) as primary damage pathways, with local stress concentrations inducing intragranular cracking. • Multi-perspective approach (triaxial tests, AE monitoring, PFC simulations) provides comprehensive understanding of microcrack evolution and failure mechanisms in granite.
Abstract
To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite, a multi-perspective approach was adopted. This approach combined triaxial compression tests, acoustic emission (AE) monitoring, and PFC simulations. The results show that: 1) Confining pressure exhibits a pronounced linear correlation with both yield strength and compressive strength. The enhancement of confining pressure significantly improves the deformability of granite and promotes a progressive shift in failure mechanism from brittle rupture to ductile deformation; 2) Increasing confining pressure elevates the stress threshold for microcrack initiation and suppresses crack propagation. As a result, the proportion of shear cracks increases (based on AE analysis) from 18.71% to 61.2%, marking a transition in the dominant failure mode from tensile to shear; 3) Confining pressure facilitates the development of grain boundary shear cracks (GBSCs), establishing the primary damage pathways. In addition, local stress concentrations under high confinement conditions trigger intragranular cracking. This highlights the regulatory effect of confining pressure on microcrack evolution.
1. Introduction
With the acceleration of national infrastructure and energy development, the stability and support of surrounding rock have become critical concerns for engineering safety [1, 2]. Complex triaxial stress conditions in deep underground engineering significantly affect the mechanical behavior of surrounding rock, leading to decreased stability and frequent geohazards [3 −5]. Therefore, elucidating the regulatory mechanisms of confining pressure on rock damage evolution is of great significance for a thorough understanding of deep rock failure processes and accurate assessment of engineering stability. Considering that brittleness significantly affects rock mass stability [6], and granite is a typical brittle rock, investigating its failure mechanisms is vital for revealing fracture evolution and guiding support design.
AE monitoring has been extensively utilized to investigate fracture mechanisms and damage progression in rocks under complex stress conditions [7 −9]. FU et al [10] investigated the influence of notch geometry on granite behavior under uniaxial compression, correlating acoustic emission (AE) activity with stress evolution. While uniaxial setups simplify AE sensor deployment, they fail to replicate the triaxial stress conditions encountered in deep rock masses. Consequently, AE monitoring under triaxial conditions has received increasing attention. HOU et al [11] identified early-warning AE indicators during sandstone unloading under variable confining pressures, while LIU et al [12] demonstrated that fracture inclination significantly alters AE spatial distribution and weakens rock integrity during rupture. Similarly, WANG et al [13] employed AE monitoring in triaxial unloading tests on shallow Beishan granite to identify crack stress thresholds and track strain energy evolution. Although these studies have explored various AE characteristics, such as spatial-temporal evolution, frequency, and amplitude, the parameter systems remain relatively fragmented. LI et al [14] further integrated AE with DIC to analyze microcrack quantity and intensity, revealing the potential of multiparameter approaches. Existing AE studies often focus on isolated parameters, and a comprehensive synthesis of spatiotemporal and multi-feature AE data under complex stress paths is still lacking in the literature.
Experimental techniques are effective for capturing the macroscopic failure behavior of rocks under varying confining pressures, but they offer limited insight into the initiation, propagation, and coalescence of internal microcracks. In contrast, numerical simulation techniques provide fine-scale mechanical insights into crack evolution mechanisms [15 −19]. Among them, PFC software has been widely applied due to its excellent capability in representing rock damage and failure.
Loading authentic research manuscript (Pages 1–5)...
XU Meng-ling, XU Nu-wen, LI Zhuang, HE Yi-fan, SUN Ling-feng, JIA Nai-ze (2025). Mechanism of confining pressure-induced failure mode transition in granite: Implications from acoustic emission and numerical simulation. Journal of Central South University. https://doi.org/10.1007/s11771-025-6132-y
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 elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite, using a multi-perspective approach combining triaxial compression tests, acoustic emission monitoring, and PFC simulations.
How does confining pressure affect granite failure mode?
Increasing confining pressure shifts the failure mode from brittle rupture to ductile deformation, and the dominant crack type transitions from tensile to shear, with shear crack proportion increasing from 18.71% to 61.2%.
What role does acoustic emission play in this research?
Acoustic emission monitoring is used to track microcrack initiation and propagation, providing data on crack types and stress thresholds, which helps in understanding the failure mechanisms under different confining pressures.
Why is numerical simulation used alongside experiments?
Numerical simulation (PFC) provides fine-scale insights into crack evolution mechanisms that are difficult to observe experimentally, allowing a more comprehensive understanding of microcrack behavior and failure processes.
What are the practical implications of this study?
The findings help in understanding deep rock failure processes, which is crucial for assessing engineering stability and designing support systems in deep underground engineering projects.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.