A Hilbert polarization imaging method with breakpoint diffracted wave in front of roadway

摘要

Advanced prediction of fault and broken wing seams has been a focus of seismic prospecting in underground coal mines. In this study, a Hilbert polarization imaging method that can locate the broken wing seam ahead of the tunneling face with high precision is put forward. This method uses Hilbert polarization analysis to calculate polarization parameters of breakpoint diffracted waves of different receivers. Through combination calculation of the polarization parameters, possibly existing diffraction points can be calculated. On this basis, with the spatial density distribution of the diffraction points as a criterion, convergence imaging is conducted on the actual breakpoint of broken wing seams. The numerical simulation results of three-dimensional, three-component advanced detection indicate that breakpoint diffracted P wave is characterized by a narrow wave train and high velocity. Since it is easy to recognize, with clear polarization characteristics, a diffracted P wave is taken as the effective wave for the Hilbert polarization imaging method. When a breakpoint diffracted S wave reaches the roadway surface, a Rayleigh surface wave is generated, which interferes with the calculation of the polarization parameter of the diffracted S wave. In this case, imaging is difficult with a breakpoint diffracted S wave. The Hilbert polarization imaging method does not need to consider the velocity modeling problem and can accurately locate broken wing seams. (C) 2020 Published by Elsevier B.V.