BLASTING, Volume. 41, Issue 4, 8(2024)

Study on Dynamic Characteristics and Fracture Mechanism of Coal Rock under Action of Mechanical-thermal Coupling

LI Peng-long1...2, LUO Ning1,2,3,*, SUO Yun-chen1,2, CHAI Ya-bo1,2, and SUN Rui12 |Show fewer author(s)
Author Affiliations
  • 1State Key Laboratory for Geomechanics and Deep Underground Engineering
  • 2School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China
  • 3State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
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    To carry out deep coal mining safely and efficiently, the dynamic mechanical characteristics and fracture mechanism of coal rock in deep earth were investigated under the ‘three high and one disturbance’ environment. A dynamic impact test of coal rock was carried out using the self-improved φ 50 mm high temperature synchronous split Hopkinson pressure bar (SHPB) test equipment at temperatures between 25~200℃. A ZWT viscoelastic constitutive model was also improved to establish a dynamic constitutive equation considering the temperature effect. The influence of high temperature on crack development law and the dynamic strength of coal rock was investigated based on the coupling of the finite difference and discrete element methods. The results show four stages to the dynamic stress-strain curve of coal rock under high-temperature impact: compaction, elastic, crack propagation, and softening failure. The dynamic compressive strength and dynamic elastic modulus of coal rock significantly decrease as temperature increases. In contrast, the failure strain increases, and the absorbed energy varies in a W-shaped pattern. The fractal dimension increases linearly as the particle size decreases. The degree and complexity of the fragmentation mechanism increase as the compressive strength decreases. Although the improved dynamic constitutive model based on ZWT could adequately express the stress-strain relationship following a high-temperature impact, it does not apply to the compaction stage. According to the simulation and test results, water and adsorbed gas actively escape in the coal rock at 150℃. The coal matrix is also heated and expanded, which induces cracks. There are apparent mesoscopic cracks initially and gradually developed through cracks, mainly shear ones. The crack development of coal rock under dynamic compression at 100℃ develops through the impact surface, and the high temperature deteriorates the strength of coal rock.

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    LI Peng-long, LUO Ning, SUO Yun-chen, CHAI Ya-bo, SUN Rui. Study on Dynamic Characteristics and Fracture Mechanism of Coal Rock under Action of Mechanical-thermal Coupling[J]. BLASTING, 2024, 41(4): 8

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    Paper Information

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    Received: Dec. 21, 2023

    Accepted: Jan. 3, 2025

    Published Online: Jan. 3, 2025

    The Author Email: Ning LUO (nluo@cumt.edu.cn)

    DOI:10.3963/j.issn.1001-487x.2024.04.002

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