Fracture Propagation Patterns and Multifractal Characteristics of Rock–Coal–Rock Composite Structures with Different Interface Inclinations
5 affiliations
- 1School of Energy and Mining Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China
- 2Coal Industry Engineering Research Center of Top-Coal Caving Mining, Beijing 100083, China
- 3Green Intelligent Mining of Thick Coal Seam Engineering Research Center of Ministry of Education, Beijing 100083, China
- 4School of Emergency Management and Safety Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China
- 5College of Safety and Ocean Engineering, China University of Petroleum-Beijing, Beijing 102249, China
Abstract
Rock–coal–rock (RCR) composite structures in inclined coal seams exhibit asymmetric deformation and inclination-dependent failure. This study investigates how coal–rock interface inclination affects mechanical response and fracture development using uniaxial compression tests, CT imaging, three-dimensional reconstruction, and multifractal analysis. As the inclination increased from 0° to 40°, load-bearing capacity decreased and the dominant failure mode changed from splitting through mixed tensile–shear failure to interface-controlled shear failure. Crack volume and surface area decreased with inclination; the crack-to-rock/coal volume ratio was 0.04 at 10°, while the crack specific surface area was 4.345 and reached a maximum of 4.432 at 40°. A pseudo-color enhancement workflow improved the identification of fine cracks that were difficult to capture by conventional binary processing. Multifractal parameters quantified crack-network complexity and revealed pronounced anisotropy among specimens and spatial heterogeneity within each specimen. Coal-bearing regions generally sustained greater damage, whereas rock regions exhibited more heterogeneous crack distributions. Correlation analysis linked the mechanical response to fracture geometry and multifractal characteristics, showing that interface inclination progressively promotes weak-plane-controlled instability. These findings clarify the fracture mechanism of inclined RCR composites and provide a basis for stability assessment in inclined coal-seam mining.
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BibTeX
@article{cui2026fracture,
title = {{Fracture Propagation Patterns and Multifractal Characteristics of Rock–Coal–Rock Composite Structures with Different Interface Inclinations}},
author = {Xuan Cui and Shengli Yang and Chunyu Duan and Kai Wang and Huiying Zhou and Aoxiang Wang},
journal = {Fractal and Fractional},
year = {2026},
month = oct,
doi = {10.3390/fractalfract10110766},
url = {https://www.mdpi.com/2504-3110/10/11/766},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Fracture Propagation Patterns and Multifractal Characteristics of Rock–Coal–Rock Composite Structures with Different Interface Inclinations
AU - Xuan Cui
AU - Shengli Yang
AU - Chunyu Duan
AU - Kai Wang
AU - Huiying Zhou
AU - Aoxiang Wang
PY - 2026
DA - 2026/10/31
JO - Fractal and Fractional
DO - 10.3390/fractalfract10110766
UR - https://www.mdpi.com/2504-3110/10/11/766
AB - Rock–coal–rock (RCR) composite structures in inclined coal seams exhibit asymmetric deformation and inclination-dependent failure. This study investigates how coal–rock interface inclination affects mechanical response and fracture development using uniaxial compression tests, CT imaging, three-dimensional reconstruction, and multifractal analysis. As the inclination increased from 0° to 40°, load-bearing capacity decreased and the dominant failure mode changed from splitting through mixed tensile–shear failure to interface-controlled shear failure. Crack volume and surface area decreased with inclination; the crack-to-rock/coal volume ratio was 0.04 at 10°, while the crack specific surface area was 4.345 and reached a maximum of 4.432 at 40°. A pseudo-color enhancement workflow improved the identification of fine cracks that were difficult to capture by conventional binary processing. Multifractal parameters quantified crack-network complexity and revealed pronounced anisotropy among specimens and spatial heterogeneity within each specimen. Coal-bearing regions generally sustained greater damage, whereas rock regions exhibited more heterogeneous crack distributions. Correlation analysis linked the mechanical response to fracture geometry and multifractal characteristics, showing that interface inclination progressively promotes weak-plane-controlled instability. These findings clarify the fracture mechanism of inclined RCR composites and provide a basis for stability assessment in inclined coal-seam mining.
SN - 2504-3110
ER -