Optical Fiber Frequency Shift Characterization of Overburden Deformation in Short-Distance Coal Seam Mining

Figure 9

Impact pressure identification curve during the mining of the face of coal seam 2^-2 (the abscissa is the face excavation distance, and the ordinate is the variation degree of the optical fiber frequency shift). (a) Face excavation distance of 36 cm. (b) Face excavation distance of 106 cm.