A dynamic ejection coal burst model for coalmine roadway collapse

دسته: , تاریخ انتشار: 25 فروردین 1400تعداد بازدید: 307
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جزئیات بیشتر

انتشار

۲۰۲۱

پایگاه داده

نشریه الزویر

نوع نگارش مقاله

مقاله پژوهشی

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scopus – master journals – JCR

ایمپکت فاکتور

۴٫۲۷۶ در سال ۲۰۲۰

شاخص H_index

۲۶ در سال ۲۰۲۱

شاخص SJR

۰٫۹۰۱ در سال ۲۰۲۰

شاخص Quartile (چارک)

Q1 در سال ۲۰۲۰

مدل مفهومی

ندارد

پرسشنامه

ندارد

متغیر

ندارد

رفرنس

دارد

قوانین استفاده

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A dynamic ejection coal burst model for coalmine roadway collapse


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A dynamic ejection coal burst model for coalmine roadway collapse

Abstract

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:

Introduction

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

۲۰۱۶, 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 [16].   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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