Buy article PDF
The purchased file will be sent to you
via email after the payment is completed.
US$ 35
|
Geomechanics and Engineering Volume 24, Number 6, March25 2021 , pages 519-529 DOI: https://doi.org/10.12989/gae.2021.24.6.519 |
|
|
|
Deformation and permeability evolution of coal during axial stress cyclic loading and unloading: An experimental study |
||
Kai Wang, Yangyang Guo, Hao Xu, Huzi Dong, Feng Du and Qiming Huang
|
||
| Abstract | ||
| In coal mining activities, the abutment stress of the coal has to undergo cyclic loading and unloading, affecting the strength and seepage characteristics of coal; additionally, it can cause dynamic disasters, posing a major challenge for the safety of coal mine production. To improve the understanding of the dynamic disaster mechanism of gas outburst and rock burst coupling, triaxial devices are applied to axial pressure cyclic loading-unloading tests under different axial stress peaks and different pore pressures. The existing empirical formula is use to perform a non-linear regression fitting on the relationship between stress and permeability, and the damage rate of permeability is introduced to analyze the change in permeability. The results show that the permeability curve obtained had "memory", and the peak stress was lower than the conventional loading path. The permeability curve and the volume strain curve show a clear symmetrical relationship, being the former in the form of a negative power function. Owing to the influence of irreversible deformation, the permeability difference and the damage of permeability mainly occur in the initial stage of loading-unloading, and both decrease as the number of cycles of loading-unloading increase. At the end of the first cycle and the second cycle, the permeability decreased in the range of 5.777 - 8.421 % and 4.311-8.713 %, respectively. The permeability decreases with an increase in the axial stress peak, and the damage rate shows the opposite trend. Under the same conditions, the permeability of methane is always lower than that of helium, and it shows a V-shape change trend with increasing methane pressures, and the permeability of the specimen was 3 MPa > 1 MPa > 2 MPa. | ||
| Key Words | ||
| cyclic loading- unloading; axial stress; gas pressure; deformation; permeability damage rate | ||
| Address | ||
| Kai Wang,Hao Xu, Huzi Dong and Feng Du: 1.) School of Emergency Management and Safety Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China 2.) Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining & Technology (Beijing), Beijing 100083, China Yangyang Guo: 1.) School of Emergency Management and Safety Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China 2.) Beijing Key Laboratory for Precise Mining of Intergrown Energy and Resources, China University of Mining & Technology (Beijing), Beijing 100083, China 3.) Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science & Technology, Qingdao, 266590, China Qiming Huang:Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science & Technology, Qingdao, 266590, China | ||