Table of Contents
Journal of Mining
Volume 2015 (2015), Article ID 235636, 9 pages
http://dx.doi.org/10.1155/2015/235636
Research Article

Laboratory Studies of Electric Current Generated during Fracture of Coal and Rock in Rock Burst Coal Mine

Faculty of Safety Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China

Received 29 August 2014; Revised 26 January 2015; Accepted 2 February 2015

Academic Editor: Luigi Toro

Copyright © 2015 Zhonghui Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Experiments show that electric current would be produced in uniaxial compression of coal and roof rock. The electric current of coal shows a rapid increasing tendency when the loading stress is greater than or equal to 0.75 which can be regarded as an omen for coal failure. The current of roof rock shows reversal tendency while loading stress is greater than or equal to 0.91 and revised from negative to positive at the main fracture and the reversal of current can be regarded as the omen of rock fracture. There are obvious differences in physical and mechanical properties, composition, and failure process between coal and rock. The dominant mechanism of electric current generated by coal is triboelectrification of coal particles and charge separation during crack propagation. The mechanism of electric current of roof rock is piezoelectric effect of quartz materials in the early stage and charge separation during crack propagation in the later stage of loading. It can be found that the rapid increasing and reversal characteristic of electric current can reflect the failure process of coal and roof rock, respectively. Thus, it can be considered the omen of coal and rock failure.