Research on instability characteristics and precursory effect of coal-rock parting-coal structures

Liu, Yang; Wang, Jianhua; Lu, Cai‐Ping; Wang, Chao; Xie, Hua-Dong; Yan, Xian-Yang

doi:10.1038/s41598-022-15738-x

Cited by 3 publications

(2 citation statements)

References 48 publications

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“…The AE technique has been widely used in the process of material damage analysis [34]. AE parameter analysis [35,36] has been used to identify the type of crack development in coal samples.…”

Section: Ae Analysis Methodsmentioning

confidence: 99%

The Effect of Pore Pressure on the Mechanical Behavior of Coal with Burst Tendency at a Constant Effective Stress

et al. 2022

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The mechanical evolution of coal is evident when the pore pressure and the surrounding stress alone influence it. However, the evolution of the mechanical response of saturated coal under the coupling effect of pore pressure and confining pressure needs further investigation. This study identifies the mechanical behaviors of burst tendency dry and saturated coal under the stress condition where confining and pore pressure simultaneously increase but keep the constant difference by conducting a series of triaxial compressions on high burst tendency dry and saturated coal samples. The results show that the elastic modulus (E) and strength (σpeak) of dry coal increase from 3.4 to 4.8 GPa and 78.5 to 92.6 MPa, respectively, and the macro shear failure angle decreases from 64.2° to 56.5° when the confining pressure increases from 9 to 15 MPa. However, these parameters show the opposite evolution law when the pore pressure increases. Furthermore, the E and σpeak of saturated coal decrease from 3.84 to 2.75 GPa and 73.4 to 60.3 MPa, respectively, and the macro shear failure angle of saturated coal increases from 64.7° to 72.4° when the confining pressure and pore pressure increase simultaneously. The coefficient μ is proposed to reveal the evolution of strength at the effective confining pressure. Furthermore, the Mohr–Coulomb failure criterion, including μ, is ameliorated for application in coal under pore pressure conditions. In addition, a model was developed to reveal the effect of a pore-rich layer on the angle of macrocracks, which was confirmed by acoustic emission. The research reveals the mechanical behavior of coal under high pore pressure. Improved Mohr–Coulomb criterion criteria provide new guidance and vision for the analysis of coal instability in high pore pressure coal seams.

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Section: Ae Analysis Methodsmentioning

confidence: 99%

The Effect of Pore Pressure on the Mechanical Behavior of Coal with Burst Tendency at a Constant Effective Stress

et al. 2022

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“…Deep coal seams have environmental characteristics such as "high in-situ stress, high gas pressure, and high gas content" [6][7][8]. Under these conditions, they are combined with the surrounding rock layers to form a "rock mass-coal mass" composite system structure [9][10][11]. The instability and failure of the overall structure is an intuitive manifestation of the occurrence of coal-rock composite dynamic disasters, and the overall structure strength is affected by conditions such as rock-layer strength, coal-seam strength, gas pressure, and special engineering geological environment, and its occurrence has enormous complexity.…”

Section: Introductionmentioning

confidence: 99%

Research on Mechanical Properties and Energy Evolution Law of Coal–Rock Assemblage with Different Gas Pressures

et al. 2022

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In order to study the mechanical failure characteristics and energy evolution law of gas-bearing coal–rock composites under different gas pressures, a uniaxial mechanical loading experiment was carried out on an upper-rock lower coal binary coal–rock assembly under different gas pressures. The changes in parameters such as compressive strength and elastic energy of the coal–rock combination were analyzed, and the energy transfer in the failure process of the gas-bearing coal–rock assemblage was studied. The results showed that the compressive strength of the combined body decreased linearly with the increase in gas pressure, and the decreasing rate of compressive strength was 6.4%, 16.3%, and 21.4%. The elastic modulus of the combined body decreased with the increase in gas pressure in a power function relationship. The energy accumulated before the peak of the rock part of the composite body and the elastic energy released after the peak, the energy accumulated before the peak of the composite body, and the energy dissipated after the peak of the coal body part all decreased with the increase in gas pressure. The variation range of the indicators K1 and K2, which reflect the influence degree of the partially accumulated elastic energy of the rock on the failure of the assemblage, were 5.85~6.68% and 7.34~9.46%, respectively.

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Experimental study on compression-shear fracture evolution process of locked segment of rock-like based on multivariate parameters

Jiang

Wan

Huang

et al. 2022

Preprint

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Locked segment of rock-like material specimens with different brittleness index were prepared by combining materials in different ratios. Compression-shear tests of rock-like material specimens with different brittleness degree were carried out by acoustic emission and Laser Doppler Vibrometer measurement. The fracture evolution process of the specimen was divided into three stages through the displacement-time curve: compaction stage and elastic deformation stage, constant deformation stage and accelerated deformation stage. The natural frequency responded obviously at the boundary point of the constant deformation stage and accelerated deformation stage, the point of natural frequency steeply dropped corresponds to the starting point of constant deformation stage, which is defined as the damage point. The point of substantial increase in the natural frequency corresponds to the starting point of accelerated deformation stage, which is defined as expansion point. There were obvious critical instability information before the failure of specimens: The natural frequency showed rise, steep drop and stable jitter; The ringing count rate and energy rate increased near the critical instability point; The b-value continued to decrease at a low level before the peak strength. Tensile failure was the main failure mode of the three specimens with different brittleness degree, the tensile failure degree increased with the increase of brittleness degree. The energy released by the specimen at failure moment increased with the increase of brittleness degree, and the b-value decreased with the increase of brittleness degree. The degree of brittleness is one of the important indexes to study the locked segment.

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Research on instability characteristics and precursory effect of coal-rock parting-coal structures

Cited by 3 publications

References 48 publications

The Effect of Pore Pressure on the Mechanical Behavior of Coal with Burst Tendency at a Constant Effective Stress

The Effect of Pore Pressure on the Mechanical Behavior of Coal with Burst Tendency at a Constant Effective Stress

Research on Mechanical Properties and Energy Evolution Law of Coal–Rock Assemblage with Different Gas Pressures

Experimental study on compression-shear fracture evolution process of locked segment of rock-like based on multivariate parameters

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