Fractal characteristics and its application in electromagnetic radiation signals during fracturing of coal or rock

Pattern Recognition of Signals for the Fault-Slip Type of Rock Burst in Coal Mines

“…As mentioned above, the rough sliding surface is smoothed under high stress before the fault-slip occurs, accompanied by the failure of coals and rocks. Studies show that the strength of the electromagnetic radiation signal is positively related to the stress state of rocks and the signals of AE and microseismic event can reflect the damage and failure degree of rocks [8,9,[11][12][13][14]. Therefore, we can determine the stress and energy states and failure degree from the variations of the electromagnetic radiation, AE, and microseismic signals near the sliding surface, which can reflect the risk of the fault-slip type of rock burst.…”

“…Many researchers have made contributions to the monitoring and early warning of rock burst and proposed many kinds of monitoring approaches (e.g., electromagnetic radiation, AE, microseismic signals, and stress) [8][9][10][11][12][13][14][15][16]. The electromagnetic radiation monitoring is an approach that obtains the stress magnitude and variations of coal and rock by monitoring the intensity and pulse of electromagnetic radiation [8]. Song et al and Liu et al investigated the approach to estimate the rock burst danger from the intensity and pulse of electromagnetic radiation and proposed an early warning criterion [9,10].…”

Fractal Characteristic of Rock Cutting Load Time Series

“…According to (5), the fractal dimension of fragments size distribution could be obtained by first developing an versus < / on ln-ln plots and determining the slope of best-fit line through the data points by linear regression method as shown in Figure 5, the correlation coefficient of 0.994 showing the cumulative mass rate and fragments size had the fractal characteristic again. According to (6), it was easy to get the fractal dimension of fragments size distribution which was equal to 1.42. According to (8), the double logarithmic curves for calculating the box-counting dimension of the time series corresponding to the fragments in Figure 3(a) was shown in Figure 6, and the correlation coefficient of 0.998 shows that the cutting load time series also followed the fractal distribution in space.…”

“…In addition, the fractal dimension can describe the evolving regularity of microscopic cracks. Wang et al [6] investigated the fractal characteristic of electromagnetic radiation time series of coal and rock failure, and they found that the variation of correlation dimension was consistent with coal or rock burst. Huang et al [7] researched on the fragments size distribution under DTH hammer reverse circulation drilling and found that the rock fragments size distribution of drillings conform to fractal distribution.…”

Coupled analysis about multi-factors to the effective influence radius of hydraulic flushing: Application of response surface methodology

“…Consequently, these coal mines are characterized by conditions of high stress and increasing gas pressure, both of which can easily trigger coal and gas outbursts (Hu et al, 2014;Wang et al, 2012a;Gonzatti et al, 2014). However, it is well-known that the methane generated in coal seams is an efficient and clean source of energy (Karacan et al, 2011;Petrow and Tanev, 2015).…”