Detection technique and application of transmission in-seam wave in thin coal seam

Aiming at the problem of serious attenuation of channel wave in thin seam and its limited distance of propagation, a method of restricted CT imaging was proposed by using the furthest in-seam wave propagation distance. Firstly, the variation of in-seam wave frequency with different thickness of coal seam was studied by theoretical derivation. Taking a 1.5m thin seam as the main research object, the attenuation characteristics of channel wave were simulated by forward modeling, and the effective propagation distance of channel wave was determined. The actual data of No. 15 coal seam in a coal mine in Shandong Province shows that the channel wave propagation distance is about 300 m. For the in-seam wave data of seam 15 in a coal mine in Shandong Province, the fault position interpreted from CT imaging using the technology coincided basically with that exposed by roadway. When processing the in-seam wave data of 1.5 m thick coal seam, with 300 m of propagation distance as the constraint condition to conduct the energy attenuation imaging on actual data, the channel wave CT imaging quality and interpretation accuracy were improved. This method takes into account the propagation characteristics of channel waves in thin coal seam, reduces the influence of attenuation, and highlights the anomalies caused by structural factors. It is useful for the development and application of thin seam channel wave detection technology.