THERMAL SCIENCE

International Scientific Journal

Kun-Chen He

,

Hai-Chun Hao

,

Chuo Zhang

STUDY ON LOADING RATE EFFECT OF FAILURE BEHAVIOR OF DEEP COAL UNDER EXTREME PRESSURE

ABSTRACT
Triaxial mechanical tests were conducted on coal at various confining pressures and loading rates using the GCTS rock mechanics testing system to investigate the influence of these parameters on the mechanical behavior and energy evolution of the coal. The results indicate that the strength of the coal initially increases and then decreases with increasing loading rate. A higher pressure enhances the coal's capacity for elastic energy accumulation, leading to a decrease in the critical loading rate. When the loading rate approaches this critical value, coal samples exhibit premature and dense crack propagation, a reduced efficiency in the conversion of external work into elastic strain energy, and a failure mode that manifests as ductile-like. Conversely, at loading rates significantly different from the critical loading rate, fewer cracks develop within the samples, the conversion of external work to elastic strain energy is more efficient, and the failure mode is brittle.
KEYWORDS
loading rate, acoustic emission, deep coal, triaxial test
PAPER SUBMITTED: 2025-08-15
PAPER REVISED: 2025-09-21
PAPER ACCEPTED: 2025-12-21
PUBLISHED ONLINE: 2026-07-25
DOI REFERENCE: https://doi.org/10.2298/TSCI250815142H
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Study on loading rate effect of failure behavior of deep coal under extreme pressure

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