Research on the technique of reflected in-seam wave detection in coal mine structure exploration

Abstract

The premise of seismic exploration lies in the difference in wave impedance (velocity × density) in the medium. As a special medium, the elastic properties of coal seam are significantly different from its roof and floor. A coal seam is usually a weak intercalated layer with low velocity and density in the coal measure strata. Therefore, the coal-rock interface is a strong reflection interface, which is conducive to seismic wave detection related to coal seam and coal seam structure. When the underground coal seam runs into geological anomalies such as goaf, fault, collapse column and magmatic intrusion, the continuity of the coal body can be destroyed laterally, and its integrity can be weakened due to stress, thus showing different density and elastic wave velocity at the coal rock interface. This provides a basis for seismic exploration. Taking the detection of the reflection channel wave in the goaf of the old kiln as an example, as the goaf is characterized by a cavity or caving zone, reflection occurs when the seismic wave propagates from the coal seam to the boundary of the goaf. The location of the goaf can be analyzed following the time-frequency characteristics of the reflection wave received. This paper adopted the new generation of high-speed and high-resolution mine seismographs to detect the reflection channel waves in a coal face in Shanxi Province. Using the collected data, the location of the goaf was determined, and this location was verified by the subsequent face drive.