Key Takeaways & Executive Findings
- •• Finer aggregate gradation increases compressive strength, elastic modulus, and post-peak stiffness of cemented rockfill. • Fracture patterns shift from unidirectional to X-shaped conjugate shear as aggregate size decreases, with cracks initiating at boundaries. • Finer gradation produces a more homogeneous crack network, enhancing post-peak load retention and causing frequent minor stress fluctuations. • Although cumulative energy dissipation is highest for coarse aggregates, finer aggregates delay rapid energy release, promoting slower redistribution and improved load resistance.
Abstract
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.
1. Introduction
Underground mining has led to large-scale ground subsidence and building damage, while simultaneously resulting in massive accumulations of coal gangue on the surface. According to statistics, in 2011, the production of industrial solid wastes was 47.5 million tons in UK, 385 million tons in Japan, 15 million tons in Australia, and the utilization rate of these wastes was about 50–60% [1,2]. In China, coal gangue accounts for 10%–20% of coal production, and it has become one of the major industrial and mineral residues. The stock of coal gangue in China has reached a billion level, with an increasing rate of 150–200 million per year [3,4].
The long-term accumulation of coal gangue in piles induces spontaneous combustion due to heat buildup [5,6], triggers landslide incidents [7], and leads to soil contamination through heavy metal ion leaching [8,9]. These issues have emerged as critical challenges demanding urgent solutions in coal-mining nations worldwide [10–12]. Coal gangue is graded and crushed to produce CRF for use as load-bearing components in building structures or for backfill mining [13,14], as shown in Fig. 1. This represents a major disposal pathway for coal gangue, while simultaneously mitigating the environmental and geological damage caused by quarrying operations.
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Zhu Li, Weibing Zhu, Qingdong Qu, Jialin Xu, Guorui Feng, Chunlei Guo, Jingmin Xu (2026). Influence of aggregate particle size on fracture behavior and energy evolution of cemented rockfill in the post-peak stage. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2026.01.003
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Frequently Asked Questions
What is the effect of aggregate particle size on the compressive strength of cemented rockfill?
Finer aggregate gradation increases the compressive strength and elastic modulus of cemented rockfill, as well as post-peak softening and residual stiffness.
How does aggregate size influence fracture patterns in cemented rockfill?
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.
What is the relationship between aggregate gradation and energy evolution in cemented rockfill?
Cumulative energy dissipation follows a coarse > medium > fine ordering, but finer aggregates delay rapid kinetic and dissipative energy release, promoting slower energy redistribution and improved load resistance.
Why is the study of aggregate size important for cemented rockfill design?
Understanding how aggregate gradation controls deformational mechanisms, crack topology, and energy partitioning provides design guidance for optimizing aggregate size and cementitious composition to enhance ductility, energy absorption, and structural reliability in underground engineering.
What methods were used to investigate the fracture behavior of cemented rockfill?
The study integrated digital image correlation, acoustic emission monitoring, and finite–discrete element simulations to investigate mechanical behavior, fracture development, and energy evolution.
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