A dynamic ejection coal burst model for coalmine roadway collapse
|نوع نگارش مقاله||
scopus – master journals – JCR
۴٫۲۷۶ در سال ۲۰۲۰
۲۶ در سال ۲۰۲۱
۰٫۹۰۱ در سال ۲۰۲۰
|شاخص Quartile (چارک)||
Q1 در سال ۲۰۲۰
خرید محصول توسط کلیه کارت های شتاب امکان پذیر است و بلافاصله پس از خرید، لینک دانلود محصول در اختیار شما قرار خواهد گرفت و هر گونه فروش در سایت های دیگر قابل پیگیری خواهد بود.
فهرست مطالب مقاله:
In this study, we established a dynamic ejection coal burst model for a coalmine roadway subject to stress, and held that the stress concentration zone at the roadway side is the direct energy source of this ejection. The formation and development of such burst undergoes three stages: (1) instability and prop- agation of the cracks in the stress concentration zone, (2) emerging of a layered energy storage structure in the zone, and (3) ejection of coal mass or coal burst due to instability. Moreover, we figured out the initial strength of periodic cracks is parallel to the maximal dominant stress direction in the stress con- centration zone and derived from the damage strain energy within the finite area of the zone based on the Griffith energy theory. In addition, we analyzed the formation process of the layered energy storage structure in the zone, simplified it as a simply supported restraint sheet, and calculated the minimum critical load and the internally accumulated elastic energy at the instable state. Furthermore, we estab- lished a criterion for occurrence of the coal burst based on the variational principle, and analyzed the coal mass ejection due to instability and coal burst induced by different intensity disturbances. At last, with the stratum conditions of Junde Coalmine as the model prototype, we numerically simulated the load dis- placement distribution of the stress concentration zone ahead of the working face disturbed by the main roof-fracture-induced dynamic load during the mining process as well as their varying characteristics, and qualitatively verified the above model.
|بخشی از متن مقاله:|
Coal burst poses a severe threat to China. Merely in the ten years from 2004 to ۲۰۱۴, as many as 35 coal burst-induced disas- ters led to more than 300 deaths and one thousand injuries. As of
2016, China had 190 mines prone to coal burst distributing in its main coal-producing areas, as shown in Fig. 1. Meanwhile, the coal mines are extending to the deeper earth at a speed of about 20 m annually, and tens of them have extended to a depth of 1000-plus m. Accompanied by the ever-increasing depth is improved in-situ stress and more complicated stope structure, which predicts more serious coal burst [1–۳].
In view of the significant destruction of such disaster, research- ers have devoted much to the mechanism of coal burst and pre- sented a series of classical theoretical models, such as strength theory, stiffness theory, energy theory, impact proneness theory, three criteria theory and instability theory [4–۱۱]. In recent years,
due to the development of interdisciplinary studies and applications of mathematic and mechanic methods in the study of coal burst, many researchers have turned their eyes to fracture mechanics, damage mechanics, fractal theory, as well as nonlinear theories such as transition, bifurcation and chaos in the study of the formation and development of coal burst [12–۱۵].
Some researchers applied ‘‘plate theory” to analyze the coal burst in underground space. Dyskin et al. analyzed the propagation mode of the cracks in the vicinity of roadway walls and the stabil- ity of sidewalls after the propagation, and believed that (1) com- pressive stress concentration leads initial cracks to steady propagation at the direction parallel to the maximal compressive stress; (2) interaction of the crack propagation with the free sur- face accelerates the propagation, and ultimately leads to destabi- lization and expansion of the cracks and the separation of crack surfaces; and (3) yield failure of the separation layers results in coal burst. Subsequently, they established a two-dimensional crack propagation model to calculate the stress at the propagation- starting position of unsteady cracks . Kang held that the relative approach and compression of the surrounding rocks of lateral stress concentration area as a multilayered and simply supported sheet. Second, we considered the sheet exposed to external force as the layered energy storage structure to accumulate elastic energy. Third, we analyzed the stability and failure process of the structure, and established a coal burst model to explore the process of initiation, development and evolution of the burst. Finally we qualitatively verified the model by numerical simulation.
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