Effect of thermal damage on the pore–fracture system during coal spontaneous combustion

Wang, Haiyan; Li, Jinglei; Dong, Zhihuizi; Fan, Cheng; Zhang, Yanwei; Chen, Xiao

doi:10.1016/j.fuel.2023.127439

Cited by 18 publications

(10 citation statements)

References 44 publications

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“…Table 1 presents the relevant data. The generated uniaxial stress–strain curve is compared with the results obtained from prior indoor tests 8 , 28 , 29 .…”

Section: Principle Of Thermal Coupling and Thermal Parametersmentioning

confidence: 99%

“…Little consideration has been given to the effect of temperature on coals with different degrees of metamorphism, and complete rock compression experiments cannot fully reveal the detailed rupture processes, especially the type of rupture 26 , It can be analyzed more intuitively from the point of view of micromechanics, and there are few methods to study the micromechanics of coal specimens at high temperatures; moreover, there are significant differences in terms of temperature on the change of internal cracks and mechanical properties of coals with different degrees of metamorphism. Therefore, in order to further investigate the changes in the mechanical properties of coal with different degrees of metamorphism and the evolution of internal cracks during coal oxidation, this paper adopts the PFC2D particle flow software, and compares the experimental results of the previous experiments while 8 , 28 , 29 and simulation experience 30 , the numerical simulations is completed.…”

Section: Introductionmentioning

confidence: 99%

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Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment

Zhang,

Lai,

Huang

et al. 2024

Sci Rep

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In order to study the effect of temperature on the structure and mechanical properties of coal with different metamorphic degree. Three coal samples with varying degrees of metamorphism were chosen for analysis. The discrete element software PFC2D is used to simulate the heat treatment and compression of coal. The findings indicate that during the heating process, low-order coal exhibits noticeable thermal cracks at an early stage, while thermal crack development in middle-order coal is concentrated in the later stages. In contrast, high-order coal demonstrates a more stable macroscopic structure. The strength and stiffness of low rank coal show the lowest value and decrease significantly within 135 °C. However, the strength and stiffness of medium rank coal decrease significantly after 135 °C. The changes of mechanical properties and damage modes of coal caused by thermal damage are often ignored, which may lead to the deviation of design and research results from the actual situation. Therefore, this study is of great significance to the prevention and control of coal mine disasters.

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“…Table 1 presents the relevant data. The generated uniaxial stress–strain curve is compared with the results obtained from prior indoor tests 8 , 28 , 29 .…”

Section: Principle Of Thermal Coupling and Thermal Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment

Zhang,

Lai,

Huang

et al. 2024

Sci Rep

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“…The connectivity between pores and fractures of different sizes is also more silky and smooth in C400. This is further confirmed by Wang's work 45 that the average pore size of the C400 coal sample is larger than that of C200. Since C200 experienced rapid expansion in the early stages, the interconnectivity between pores and fractures is poorer than that in C400, resulting in a fractal dimension greater than that of C400 for C200 despite its small dimension compared with RC due to its rapid development in the early stage.…”

Section: Calculation and Analysis Of Fractal Dimension Based On The M...mentioning

confidence: 99%

Study of the Microstructure of Coal at Different Temperatures and Quantitative Fractal Characterization

Huo

Wang

et al. 2023

ACS Omega

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In order to understand the influence of underground coal fires on coal fractures and pores, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) are combined to study the development of coal pore and fracture under high-temperature treatment and calculate the fractal dimension to analyze the relationship between the development of coal pore and fracture and the fractal dimension. The results show that the volume of pores and fractures of the coal sample (C200) treated at 200 °C (0.1715 mL/g) is greater than that of the coal sample (C400) treated at 400 °C (0.1209 mL/g), and both are greater than the original coal sample (RC) (0.1135 mL/g). The volume increase is mainly due to mesopores and macropores, and the proportions of mesopores and macropores in C200 were 70.15 and 59.97% in C400. The MIP fractal dimension shows a decreasing trend with the increase of temperature, and the connectivity of coal samples improved with the increase of temperature. The changes in volume and three-dimensional fractal dimension of C200 and C400 showed the opposite trend and are related to the different stress of coal matrix at different temperatures. The experimental SEM images confirm that the connectivity of coal fractures and pores improves with the increase of temperature. Based on the SEM experiment, the larger the fractal dimension, the more complex the surface is. The SEM surface fractal dimensions indicate that the surface fractal dimension of C200 is the smallest and that of C400 is the largest, which is consistent with the observations made by SEM. The combination of the two fractal dimensions is used to characterize the self-similarity of coal using the fractal dimension difference. When the temperature increased to 200 °C, the unordered expansion of the coal sample resulted in the largest fractal dimension difference and the lowest self-similarity. When heated to 400 °C, the fractal dimension difference of the coal sample is the smallest, and the microstructure of coal shows a regular groove-like development.

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“…The pore and fracture structures are developed at the nanometer to centimeter scale, which control the adsorption, desorption, diffusion, and seepage processes of a fluid in coal. , There are two main methods for the observation and analysis of pore and fracture structures in porous media: indirect imaging and direct imaging. Indirect methods include mercury injection, gas adsorption, and nuclear magnetic resonance. , Direct methods include scanning electron microscopy, field emission scanning electron microscopy, and X-ray computed tomography (i.e., CT). , The comparative analysis of various test methods shows that X-ray CT is a nondestructive three-dimensional (3D) imaging technology, which can use high-resolution images to visualize topological samples and their spatial distribution of pore and fracture structures. , …”

Section: Introductionmentioning

confidence: 99%

3D Reconstruction of Pore and Fracture Structures in Crushed Soft Coal with Low Permeability and Its Permeability Analysis: Implications for the Design of CO₂ Injection and CH₄ Production

Wang,

Fang,

Cao

et al. 2023

ACS Omega

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Effect of thermal damage on the pore–fracture system during coal spontaneous combustion

Cited by 18 publications

References 44 publications

Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment

Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment

Study of the Microstructure of Coal at Different Temperatures and Quantitative Fractal Characterization

3D Reconstruction of Pore and Fracture Structures in Crushed Soft Coal with Low Permeability and Its Permeability Analysis: Implications for the Design of CO₂ Injection and CH₄ Production

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Effect of thermal damage on the pore–fracture system during coal spontaneous combustion

Cited by 18 publications

References 44 publications

Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment

Numerical simulation study on the evolution law of mechanical properties of different metamorphic coals after heat treatment

Study of the Microstructure of Coal at Different Temperatures and Quantitative Fractal Characterization

3D Reconstruction of Pore and Fracture Structures in Crushed Soft Coal with Low Permeability and Its Permeability Analysis: Implications for the Design of CO2 Injection and CH4 Production

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3D Reconstruction of Pore and Fracture Structures in Crushed Soft Coal with Low Permeability and Its Permeability Analysis: Implications for the Design of CO₂ Injection and CH₄ Production