Research on multi-frequency electromagnetic wave CT synchronouspenetration technology in gas abundance zone

In order to verify the gas abundance zone of the mining face, numerical simulations of electromagnetic wave attenuation curves and perspective tomography features of different frequencies in different media and gas enrichment zones were carried out, based on the electromagnetic wave CT theory and SIRT tomography. A multi-frequency electromagnetic wave synchronous penetration technology was proposed, and a multi- frequency electromagnetic wave CT synchronous penetration test was carried out in Yanmazhuang Coal Mine. The results show that electromagnetic wave CT can effectively detect the gas abundance zone. Compared with normal coal, the abundance zone of gas was characterized by weak attenuation of electromagnetic wave, and the higher the frequency, the more serious the attenuation.The attenuation amplitude of high frequency electromagnetic wave was slightly larger, which had the characteristics of strong response and short perspective. Multi-frequency synchronous penetration technology, with its high efficiency and precision in penetrating detection, can ensure the high sensitivity and strong response of high frequency and the long effective perspective distance of low frequency. The underground field test results verify that the multi-frequency electromagnetic wave CT synchronous penetration technology can effectively and accurately identify the gas abundance area in the mining face, and can promote the application of coal mine production.