Electromagnetic radiation characteristics of coal under multiple loading methods and its relationship with porosity

Abstract This study deploys cyclic loading and multi-stage loading methods to study the influence of the loading method on electromagnetic radiation (EMR) characteristics in the failure process of coal. For this purpose, these methods were applied to Sihe coal samples. The EMR signals were collected...
Ausführliche Beschreibung

Abstract This study deploys cyclic loading and multi-stage loading methods to study the influence of the loading method on electromagnetic radiation (EMR) characteristics in the failure process of coal. For this purpose, these methods were applied to Sihe coal samples. The EMR signals were collected during the experiments. The varying relationship between the EMR characteristics of the loaded coal and the porosity was analyzed based on the porosity of coal samples measured by small-angle X-ray scattering (SAXS) experiments. The results indicated that the EMR signals magnify with the increase of axial stress and decline with the decrease of axial stress. The generation of the EMR pulse and amplitude under the multi-stage loading conditions is relatively smooth during the constant load stage, but the number of EMR pulses increases when the stress increases from one level to another. Moreover, the results indicated that the EMR characteristics and porosity changes are closely related to the opening, closing, and development state of pores and fractures inside the coal. These findings provide the means necessary to establish the relationship between the EMR pulse cumulative counting and the porosity of the loaded coal. During the failure process, the change in EMR pulses cumulative counting follows after the alteration in the porosity. The amount of change in both parameters reaches the maximum when the coal fails. The maximum cumulative counting of EMR pulses was 1,111,114 and 37,464 for cyclic and graded loading conditions, respectively. At the same time, the change of porosity of the loaded coal also reaches the maximum. Ausführliche Beschreibung