Three Dimensional Numerical Simulation And Wave Field Analysis Of Channel Waves In Viscoelastic VTI Media

Fine detection of geological structure in working face can provide strong geological guarantee for safe and efficient production.At present,channel wave seismic exploration is one of the effective geophysical methods to solve the geological problems of coal mines,and it is an effective geological guarantee technology.Aiming at this problem,this paper takes viscoelastic anisotropic coal seam as the research object,applies Thomsen equivalent medium theory,adopts Kelvin-Voigt viscoelastic model,and constructs viscoelastic vertical transverse isotropic(VTI)medium theory model.The influence of different physical parameters on the dynamic characteristics of channel wave propagation is studied,the influence of roadway space on channel wave field is analyzed.Summarize the channel wave response regularity of hidden structures such as faults and collapse columns in the working face.The results show that:(1)The channel wave in the viscoelastic medium model is not only affected by the wave front diffusion and dispersion attenuation,but also by the absorption attenuation of the medium.When the coal seam Qs attenuates to 10,the fundamental-order channel wave can hardly be received,and the refracted longitudinal wave and the first-order Rayleigh channel wave can still be clearly received.The latter two waves may be used as effective waves to detect the structure in the working face to make up for the shortcomings of conventional channel wave exploration methods.(2)The velocity of channel wave in VTI media model is larger than that in isotropic media model.With the increase of coal seam γ,the velocity difference of channel wave increases further.(3)The viscoelasticity and vertical transverse isotropy(VTI)of coal seam are relatively independent and have little influence on each other.Viscoelasticity affects the energy attenuation of channel waves.VTI parameters have a great influence on the velocity of channel waves.In the model without roadway,the development of X and Y components channel wave is poor,and the development of Z component channel wave is slightly better.(4)The transmission and diffraction of high-order Rayleigh channel waves occur after they encounter faults,resulting in new converted wave groups.When the fault is not completely disconnected,the energy of reflected channel wave and converted wave group increases with the increase of fault distance.After the fault is completely disconnected,with the increase of the fault distance,the energy of the reflected channel wave and the converted wave group does not change significantly.(5)The waveform and energy of the channel wave change obviously after encountering the collapse column,and the diffraction channel wave and conversion channel wave are generated at the same time.As the radius of the collapse column increases,the energy of the diffracted channel wave and the converted channel wave increases,and the energy of the Rayleigh channel wave decreases.The numerical simulation results of this paper deepen the understanding of the propagation law and geological structural response characteristics of channel wave in viscoelastic VTI media,and which provide theoretical support for the application of channel wave seismic exploration in practice.Figure [63] Table [9] Reference [100]...