Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths
This study proposes a novel cyclic stress path with simultaneous axial and confining stress and conducts triaxial testing on raw coal over various cycle periods. The analysis of bias stress–strain curves, deformation parameters, and energy indexes elucidated the mechanical and energy evolution patte...
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MDPI AG
2025-02-01
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| author | Yue Jiang Xingfeng Mao Dongming Zhang Xiang Yang |
| author_facet | Yue Jiang Xingfeng Mao Dongming Zhang Xiang Yang |
| author_sort | Yue Jiang |
| collection | DOAJ |
| description | This study proposes a novel cyclic stress path with simultaneous axial and confining stress and conducts triaxial testing on raw coal over various cycle periods. The analysis of bias stress–strain curves, deformation parameters, and energy indexes elucidated the mechanical and energy evolution patterns of coals under novel stress routes. The three deformation parameters can well reflect the deformation characteristics of the specimens. The last few cycles saw an increase in Poisson’s ratio and irreversible deformation, indicating that the coal samples were likely to crack. Specimens are more prone to instability and destruction due to increased expansion under high frequency loading. To explore the energy evolution, the energy percentage and damping ratio are added to the previously mentioned basic energy indexes. Faster cyclic period reduces specimen microstructure stability, increases mineral particle misalignment friction, and raises dissipated energy percentage and damping ratio. <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mi>S</mi></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula> based on deformation parameters and cumulative dissipated energy, respectively, can characterize the coal’s three damage stages of “deceleration–stabilization–acceleration”. Both damage variables accumulate faster in the acceleration damage stage due to cyclic period acceleration. |
| format | Article |
| id | doaj-art-7002e39ef81340fdb5d6a3a6fea69bea |
| institution | OA Journals |
| issn | 2076-3417 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | MDPI AG |
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| series | Applied Sciences |
| spelling | doaj-art-7002e39ef81340fdb5d6a3a6fea69bea2025-08-20T02:01:21ZengMDPI AGApplied Sciences2076-34172025-02-01154216710.3390/app15042167Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress PathsYue Jiang0Xingfeng Mao1Dongming Zhang2Xiang Yang3School of Information Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaSchool of Emergency Management and Safety Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaSchool of Emergency Management and Safety Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaSchool of Emergency Management and Safety Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaThis study proposes a novel cyclic stress path with simultaneous axial and confining stress and conducts triaxial testing on raw coal over various cycle periods. The analysis of bias stress–strain curves, deformation parameters, and energy indexes elucidated the mechanical and energy evolution patterns of coals under novel stress routes. The three deformation parameters can well reflect the deformation characteristics of the specimens. The last few cycles saw an increase in Poisson’s ratio and irreversible deformation, indicating that the coal samples were likely to crack. Specimens are more prone to instability and destruction due to increased expansion under high frequency loading. To explore the energy evolution, the energy percentage and damping ratio are added to the previously mentioned basic energy indexes. Faster cyclic period reduces specimen microstructure stability, increases mineral particle misalignment friction, and raises dissipated energy percentage and damping ratio. <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mi>S</mi></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>D</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula> based on deformation parameters and cumulative dissipated energy, respectively, can characterize the coal’s three damage stages of “deceleration–stabilization–acceleration”. Both damage variables accumulate faster in the acceleration damage stage due to cyclic period acceleration.https://www.mdpi.com/2076-3417/15/4/2167cyclic loading and unloadingdifferent cyclic periodsdeformation characteristicsenergy evolutiondamage variable |
| spellingShingle | Yue Jiang Xingfeng Mao Dongming Zhang Xiang Yang Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths Applied Sciences cyclic loading and unloading different cyclic periods deformation characteristics energy evolution damage variable |
| title | Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths |
| title_full | Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths |
| title_fullStr | Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths |
| title_full_unstemmed | Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths |
| title_short | Experimental Study on Mechanical Deformation and Energy Evolution of Deep Coal Under Complex Stress Paths |
| title_sort | experimental study on mechanical deformation and energy evolution of deep coal under complex stress paths |
| topic | cyclic loading and unloading different cyclic periods deformation characteristics energy evolution damage variable |
| url | https://www.mdpi.com/2076-3417/15/4/2167 |
| work_keys_str_mv | AT yuejiang experimentalstudyonmechanicaldeformationandenergyevolutionofdeepcoalundercomplexstresspaths AT xingfengmao experimentalstudyonmechanicaldeformationandenergyevolutionofdeepcoalundercomplexstresspaths AT dongmingzhang experimentalstudyonmechanicaldeformationandenergyevolutionofdeepcoalundercomplexstresspaths AT xiangyang experimentalstudyonmechanicaldeformationandenergyevolutionofdeepcoalundercomplexstresspaths |