Coal seams have a pronounced bedding structure with developed cracks and exhibit signifi cant anisotropy.However,few studies have examined the frequency dispersion properties of channel waves in anisotropic coal seams...Coal seams have a pronounced bedding structure with developed cracks and exhibit signifi cant anisotropy.However,few studies have examined the frequency dispersion properties of channel waves in anisotropic coal seams.In this study,numerical solutions are calculated using the generalized reflection–transmission coefficient method for the dispersion curves of Love channel waves in vertical transversely isotropic(VTI)and horizontal transversely isotropic(HTI)medium models.Moreover,the frequency dispersion characteristics of Love channel waves in several typical transversely isotropic models are analyzed.We fi nd that the dispersion curves for isotropic and VTI media diff er signifi cantly.In addition,the phase and Airy-phase velocities in VTI media are higher than those in isotropic media.Thus,neglecting this difference in practical channel wave detection will result in large detection errors.The dispersion curves for the isotropic and HTI media do not differ signifi cantly,and the Airy-phase velocities of various modes are similar.The group-velocity curve for a coal seam model containing a dirt band is found to be extremely irregular.The fundamental-mode Airy phase is not pronounced,but the fi rst-mode Airy phase can be clearly observed.Hence,fi rst-mode channel waves are suitable for detecting dirt bands.展开更多
基金supported by the National Key R&D Program of China (No. 2018YFC0807804-3)Key R&D Program of Anhui Province (No. 1804a0802213)Scientifi c Research Foundation for the introduction talent of Anhui University of Science and Technology。
文摘Coal seams have a pronounced bedding structure with developed cracks and exhibit signifi cant anisotropy.However,few studies have examined the frequency dispersion properties of channel waves in anisotropic coal seams.In this study,numerical solutions are calculated using the generalized reflection–transmission coefficient method for the dispersion curves of Love channel waves in vertical transversely isotropic(VTI)and horizontal transversely isotropic(HTI)medium models.Moreover,the frequency dispersion characteristics of Love channel waves in several typical transversely isotropic models are analyzed.We fi nd that the dispersion curves for isotropic and VTI media diff er signifi cantly.In addition,the phase and Airy-phase velocities in VTI media are higher than those in isotropic media.Thus,neglecting this difference in practical channel wave detection will result in large detection errors.The dispersion curves for the isotropic and HTI media do not differ signifi cantly,and the Airy-phase velocities of various modes are similar.The group-velocity curve for a coal seam model containing a dirt band is found to be extremely irregular.The fundamental-mode Airy phase is not pronounced,but the fi rst-mode Airy phase can be clearly observed.Hence,fi rst-mode channel waves are suitable for detecting dirt bands.
