Influence of Local Frequent Dynamic Disturbance on Micro-structure Evolution of Coal-Rock and Localization Effect
- PDF / 6,026,370 Bytes
- 26 Pages / 595.276 x 790.866 pts Page_size
- 62 Downloads / 204 Views
Original Paper
Influence of Local Frequent Dynamic Disturbance on Micro-structure Evolution of Coal-Rock and Localization Effect Huan Zhang ,1,4 Hongbao Zhao,2,4 Wenpu Li,1 Xuelin Yang,1 and Tao Wang3 Received 5 January 2020; accepted 24 April 2020
This study aimed to investigate the influence of local frequent dynamic disturbance on micro-structure evolution in different zones of coal-rock. To do so, we carried out a systematic experimental research on the micro-structure evolution of briquette and raw coal samples under local impact load by using self-developed pendulum hammer dynamic impact loading test device of coal-rock and ultrasonic testing equipment, and analyzed the localization effect of local impact load. The results show that Mn (micro-structure cumulative change factor) of briquette coal samples presents an inclined M-shaped four-stage evolution mode along and perpendicular to impact direction with cyclic impact times under conventional full impact load, whereas it shows more obvious anisotropy and localization under local impact load. Mn for both conventional full impact and local impact shows a nonlinear increasing trend with the increase in impulse, but their increasing gradients are different. The critical zone is the most affected, the impact zone comes next, and the non-impact zone is the least affected with the increase in impulse under local impact load. Mn in the impact zone and critical zone decreases exponentially with the increase in the impact loading area, while it increases exponentially in the non-impact zone. The micro-structures evolution in briquette and raw coal samples is similar, but the anisotropy and localization effect of microstructure evolution for raw coal samples are more significant and more sensitive to the impact loading area. The micro-structure evolution of coal-rock under local impact load shows obvious localization effect. Mn in the critical zone is usually the largest, Mn in the impact zone is slightly less than that in the critical zone, and Mn in the non-impact zone is the least. The larger the impact loading area, the wider the influence enhancement area, and the smaller the non-influence area, yet the smaller the impact zone and critical zone are affected by local impact load. KEY WORDS: Coal-rock, Local impact load, Micro-structure evolution, Micro-structure cumulative change factor, Localization effect.
1
School of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China. 2 State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang 050043, China. 3 School of Energy and Mining Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China. 4 To whom correspondence should be addressed; e-mail: [email protected], [email protected]
INTRODUCTION Coal-rock and various types of rock are significant engineering medium. They are closely related to the development of various industries, such as min
Data Loading...
