Experimental research on electrical resistivity variation of coal under different loading modes
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ORIGINAL PAPER
Experimental research on electrical resistivity variation of coal under different loading modes Xiangchun Li 1 & Qi Zhang 1
&
Zhenxing An 1 & Xiaolong Chen 1 & Fan Zhang 1
Received: 11 January 2020 / Accepted: 18 September 2020 # Saudi Society for Geosciences 2020
Abstract In order to investigate the variation regularity of coal mass electrical resistivity in a complex stress environment, a real-time testing system of resistivity variation regularities of coal under loading was established in this study. Through this testing system, resistivity variations of coal mass under uniaxial compression, cyclic loading, multi-stage loading, stress relaxation, and creep loading were tested, respectively. Also, field emission scanning electron microscopy (FE-SEM) was carried out on coal mass. Ultimately, the variation characteristics and micro-mechanism of coal mass resistivity under different loading modes were discussed in depth. The research results indicated that the electrical resistivity of the coal mass varies with stress under different loading modes. The results also suggested that there are great correlations between axial stress, axial strain, and resistivity. Furthermore, it was found that the variation regularity of coal mass electrical resistivity changes with the change of pore structure during mechanical loading. Considering the variations of the axial stress and porosity during uniaxial compression, it was also demonstrated that the electrical resistivity of the coal mass is dominated by its pore structure and characteristics. Keywords Coal mass . Electrical resistivity . Loading modes . FE-SEM scanning . Pore structure
Introduction The stress field environment of coal and rock mass becomes more complicated with the increase of mining depth and intensity (Song et al. 2018). Also, the coal and gas outburst, rock burst, and other coal rock dynamic disasters have been a persistent threat to mine safety (Li et al. 2019). During the evolution of coal rock dynamic disasters, there are many physical and mechanical response mechanisms involved in the process (Nie et al. 2009). Besides, the electrical resistivity is an important parameter reflecting the minute changes and fundamental characteristics of the internal structure of coal mass. It is also a crucial parameter for early warning of coal rock dynamic disasters (Dong 2013; Maillet 1947; Jin et al. 2011). The study of the coal mass resistivity under different loading
Responsible Editor: Murat Karakus * Qi Zhang [email protected] 1
School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
modes can provide critical parameters and practical significance for the evolution and prediction of coal rock dynamic disasters during coal mining (Chen and Wang 2013). During the excavation of underground engineering, the equilibrium state of the in situ stress field is disturbed due to the breakage of the rock structure. Hence, the stress existing in the coal mass is redistribute
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