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Experimental study on energy evolution and damage characteristics of unloading coal under cyclic loading
Peng Zou1, Hao Fan2, Huaiqian Liu1
1State Key Laboratory Mine Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, China.
Scientific Reports
|May 13, 2025
Summary
Deep coal mining involves cyclic loading and unloading. This study analyzed coal failure under these conditions, developing an energy-damage model to improve mining safety and stability control.
Area of Science:
- Geotechnical Engineering
- Rock Mechanics
- Mining Engineering
Background:
- Deep coal mining faces challenges from vertical cyclic loading and lateral unloading.
- Understanding coal failure under these specific mechanical conditions is crucial for safe extraction and mine stability.
Purpose of the Study:
- To investigate the energy evolution and damage characteristics of coal under cyclic loading and varying confining pressures.
- To develop and validate an energy-damage constitutive model for predicting coal failure behavior.
Main Methods:
- Cyclic loading tests were performed on unloaded coal samples using an MTS816 system.
- Energy evolution and stress-strain curves were analyzed.
- CT scanning was employed to examine post-test fracture distribution and characteristics.
- An energy-dissipation-based constitutive model was developed and validated.
Main Results:
- Increased stress level and confining pressure enhance coal's energy storage and dissipation capacity, primarily as elastic energy.
- Coal damage increases with stress levels, with significant divergence in damage curves under different confining pressures.
- Fractal dimensions and fracture volumes initially increase then decrease with rising confining pressure, indicating complex failure patterns.
Conclusions:
- The developed energy-damage constitutive model accurately describes the deformation behavior of coal under cyclic loading.
- Findings provide a valuable reference for controlling coal stability in deep mining environments subjected to cyclic loading.
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