Mechanical Properties and Damage Behavior of Rock-Coal-Rock Combined Samples under Coupled Static and Dynamic Loads

Bai, Jinzheng; Li, Dou; Małkowski, Piotr; Li, Jiazhuo; Zhou, Kunyou; Chai, Yanjiang

doi:10.1155/2021/3181697

Cited by 10 publications

(4 citation statements)

References 36 publications

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“…It can be seen that when other external conditions are similar, the loading rate v is correlated with the compressive strength, and the compressive strength increases with the increase of loading rate v , which is similar to the data obtained in other related studies. 46 − 49 Therefore, the experimental results have high reliability, and the experimental results have a certain universality. However, it can also be seen from the results that the compressive strength of composite coal-rock is not constant under the same loading rate v, whose numerical fluctuation range is 1–2 MPa, and the results have a certain degree of dispersion, which is related to the difference of physical property parameters caused by the different sampling locations of different coal and rock samples.…”

Section: Experimental Analysismentioning

confidence: 99%

Stress-Electromagnetic Radiation (EMR) Numerical Model and EMR Evolution Law of Composite Coal-Rock under Load

Yang

et al. 2022

ACS Omega

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There is a close relationship between the electromagnetic radiation (EMR) evolution and the stress state during loading of composite coal-rock. In this research, the coal-rock EMR generation mechanism was studied and the stress-EMR numerical model was established. Finite element simulation and experiments were then used to verify their correctness, and EMR characteristics, evolution law, and the corresponding relationship between EMR and coal-rock state were studied in depth. The results show that the deformation cycle of “load compression–deformation release–load compression” occurs at coal-rock internal fractures, which together with friction make the formation of coal-rock alternating weak current sources, resulting in the EMR. In addition, the fracture structure is similar to capacitors with time-varying electric quantity and plate spacing. When the fracture is loaded, it will generate approximately sinusoidal EMR pulses whose amplitude is positively correlated with the degree of coal-rock damage. EMR will be exponentially attenuated and distorted at the medium junction when propagating, which does not affect signal characteristics. Meanwhile, EMR quality within 1.0–2.5 mm outside coal-rock is high, whose change is almost synchronous with source. EMR evolution has stages during loading, whose characteristics are different in each stress stage: In compaction and elastic stages, EMR remains stable for most of the time except for the abrupt change of 1–3 mV/m at the junction. In the yield, coal-rock transitions from elastic to plastic, and both EMR and stress increase rapidly as fracture expands. In the fracture stage, EMR maintains high and produces a peak that is synchronous with the stress. After fracture, they drop and recover to stability. The research results will help improve the basic theory of coal and rock dynamic disasters and provide support for its prediction with multi-information fusion, which will help reduce the adverse impact of coal mine disasters on people’s lives and property.

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Section: Experimental Analysismentioning

confidence: 99%

Stress-Electromagnetic Radiation (EMR) Numerical Model and EMR Evolution Law of Composite Coal-Rock under Load

Yang

et al. 2022

ACS Omega

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“…The process of deformation and failure of coal under compression usually goes through four stages: energy input, accumulation, dissipation, and release. A scholar has defined the cumulative dissipated energy density of the experiment [27]. It is assumed that the temperature is constant during the test, and there is no heat exchange between the physical process and the outside world.…”

Section: Mechanical Properties Of Coal Samples Under the Influence Of...mentioning

confidence: 99%

Mechanical Behavior Characteristics and Energy Evolution Law of Coal Samples under the Influence of Loading Rate—A Case Study of Deep Mining in Wudong Coal Mine

et al. 2022

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In order to clarify the mechanical properties and energy changes of coal samples under the influence of mining depth, a mechanical test analysis method to determine that the increase in mining depth increases the loading rate has been developed. Taking the Wudong Coal Mine as an example, a mechanical test analysis of coal samples is carried out. The results show that the surface deformation and failure of coal samples in the loading process presents four stages. That is, the evolution process of ‘complete coal sample’–‘partial failure-failure extension’–‘overall instability’. The maximum temperature of a coal sample when it is destroyed shows an obvious nonlinear increasing trend with the increase in loading rate. With the increase in loading rate, the strength and elastic modulus of coal samples decrease gradually. The cumulative total energy and elastic energy of coal samples are linearly positively correlated with the loading rate. The research results provide ideas for rational control of mining intensity and determination of productivity in steeply inclined thick coal seams for deep mining.

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“…Chai et al (2023) performed uniaxial static-cyclic loading tests on a series of combined bodies with different roof lithologies, and investigated the damage and failure process of combined bodies under mining-induced stress conditions, particularly the mechanical response and damage evolution of coal and rock under cyclic disturbance. Bai et al (2021) conducted uniaxial cyclic dynamic loading experiments with four different coal height ratios of combined bodies, analyzed the mechanical properties, failure modes, and wave velocity evolution of combined bodies, discussed the process of rock burst under coupled static and dynamic loads in rock-coal-rock combined body. Zuo et al (2018) conducted the uniaxial compression test on the coal-rock combined specimen of Qianjiaying coal and found the phenomenon of joint failure of coal and rock, which was mainly due to the rock failure caused by the elastic property released by the coal body at the time of failure.…”

Section: Introductionmentioning

confidence: 99%

Coal-rock combined body failure mechanism based on crack distribution characteristics

Chen

2024

Acta Geodynamica Et Geomaterialia

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Many papers on axial compression tests of coal-rock combined bodies have observed the failure of rock components. However, the failure mechanism of the rock component has been the focus of debate among many scholars. One view is that the failure of the rock is due to the energy released during coal failure; the other view is that the failure of the rock is due to the inconsistent coal-rock lateral deformation resulting in tensile stress on the rock side of the coal-rock interface. In response to these two controversial failure mechanisms, coal-rock combined bodies with three coal-rock interface bonding methods (AB glue, direct contact, and graphite fluoride) were designed, and the axial compression tests were carried out. The results show that: (1) the damage cracks of the combined body are mainly distributed on the coal component, the stronger the interface adhesion, the easier it is to crack. (2) All three combined bodies showed rock component damage, and the number of cracks in the rock component was different at different interfaces of the combined bodies. The stronger the interfacial adhesion is, the easier it is to produce cracks, and the more the number of cracks in the rock component is. (3) The destruction of rock components is the result of energy transfer mechanism. Under the action of the test machine, the coal component is destroyed first, and a large amount of elastic energy is released instantaneously to the rock component, which reaches the energy storage limit of the rock and stimulates the destruction of the rock component. The tensile stress at the coal-rock interface plays a certain role in the propagation and penetration of cracks in the rock, but does not determine the damage of rock components. (4) The stronger the interfacial bonding, the greater the strength of the combined body. Based on the D-P criterion, the strength of coal rock at the interface of coal-rock combined body was analyzed. The strength of the coal body at the interface increases to a certain extent, and the strength of the rock mass at the interface decreases to a certain extent. ( 5) The stress distribution model of coal-rock combined body was constructed, and the internal mechanism of coal-rock component failure was further clarified. The coal and rock mass at the interface are the weak areas of the combined body, and the stress concentration in this area is the largest and the possibility of damage is the largest.

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Mechanical Properties and Damage Behavior of Rock-Coal-Rock Combined Samples under Coupled Static and Dynamic Loads

Cited by 10 publications

References 36 publications

Stress-Electromagnetic Radiation (EMR) Numerical Model and EMR Evolution Law of Composite Coal-Rock under Load

Stress-Electromagnetic Radiation (EMR) Numerical Model and EMR Evolution Law of Composite Coal-Rock under Load

Mechanical Behavior Characteristics and Energy Evolution Law of Coal Samples under the Influence of Loading Rate—A Case Study of Deep Mining in Wudong Coal Mine

Coal-rock combined body failure mechanism based on crack distribution characteristics

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