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中南大学学报(英文版)

Journal of Central South University

Vol. 24    No. 2    February 2017

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Effects of water intrusion and loading rate on mechanical properties of and crack propagation in coal–rock combinations
CHEN Tian(陈田), YAO Qiang-ling(姚强岭), WEI Fei(卫斐), CHONG Zhao-hui(种照辉), ZHOU Jian(周健), WANG Chang-bin(王常彬), LI Jing(李静)

School of Mines, Key Laboratory of Deep Coal Resource Mining of Ministry of Education of China,China University of Mining & Technology, Xuzhou 221116, China

Abstract:Tackling the problems of underground water storage in collieries in arid regions requires knowledge of the effect of water intrusion and loading rate on the mechanical properties of and crack development in coal–rock combinations. Fifty-four coal–rock combinations were prepared and split equally into groups containing different moisture contents (dry, natural moisture and saturated) to conduct acoustic emission testing under uniaxial compression with loading rates ranging from 0.1 mm/min to 0.6 mm/min. The results show that the peak stress and strength-softening modulus, elastic modulus, strain-softening modulus, and post-peak modulus partly decrease with increasing moisture content and loading rate. In contrast, peak strain increases with increasing moisture content and fluctuates with rising loading rate. More significantly, the relationship between stiffness and stress, combined with accumulated counts of acoustic emission, can be used to precisely predict all phases of crack propagation. This is helpful in studying the impact of moisture content and loading rate on crack propagation and accurately calculating mechanical properties. We also determined that the stress thresholds of crack closure, crack initiation, and crack damage do not vary with changes of moisture content and loading rate, constituting 15.22%, 32.20%, and 80.98% of peak stress, respectively. These outcomes assist in developing approaches to water storage in coal mines, determining the necessary width of waterproof coal–rock pillars, and methods of supporting water-enriched roadways, while also advances understanding the mechanical properties of coal–rock combinations and laws of crack propagation.

 

Key words: water intrusion; loading rate; mechanical properties; coal-rock combination; crack propagation; stress threshold

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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