Analysis of quality factors for Rayleigh channel waves

To facilitate investigation of the effect of imperfect elastic dissipation on the propagation of Rayleigh-type channel waves and use of their quality factors in investigations of the properties of coal seams, a simple method for calculating the quality factor Q _R is proposed in this paper. Introduction of complex velocities into the dispersion function allows calculation of the dispersion function of Rayleigh-type channel waves in coal seams. By the control variable method, we analyzed changes in Q _R with changes in coal seam thickness and P- and S-wave Q-factors within the coal seam and adjacent rock layers. The numerical results show that the trend of the Q _R curve is consistent with the group velocity curve. The minimum Q _R value occurs at the Airy phase frequency; the Airy phase frequency decreases as coal seam thickness increases. The value of Q _R increases with increasing Q _S2 (quality factor for S wave in coal seam). We can compensate for the absorption of Rayleigh-type channel waves using the computed Q _R curve. Inversion of the Q _R curve can also be used to predict the thicknesses and lithologies of coal seams.