356 / 2018-05-30 16:53:38

Study on the propagation rules of ultrasonic wave in the coal samples with hole

ultrasonic wave, propagation rules, coal samples with hole, kinematics characteristic parameter, dynamic characteristic parameter

矿山动力灾害 > 采空区

Based on ultrasonic propagation theory and the seismic wave theory, the objective of the paper is to analyze the ultrasonic propagation rules in coal samples with small manmade boreholes, and then provide academic reference for the seismic explore in the colliery. For this purpose, the theory analysis, experimental investigations and numerical simulation are applied to analyze the ultrasonic propagation characteristics in coal samples with boreholes. The results show that with the increase of boreholes' incline angle from 0° to 90° in coal samples, the transmission coefficient decrease linearly, and the attenuation parameter increase linearly. And for the coal samples, the ultrasonic dynamic characteristic parameters(amplitude and attenuation parameter) is much more sensitive to the kinematics characteristic parameter(velocity). The 3-D numerical simulation results present that there are phenomena of reflection, scattering, and a little obvious diffraction when the ultrasonic wave goes through the coal samples with different angle boreholes, and with the increase of the diameter of borehole in coal samples, the amplitude values decrease and the attenuation parameters increase linearly respectively, which is in good agreement with experimental results. And then with the increase of borehole diameter and the test frequency respectively, the more the amplitude values decrease, the more the attenuation increase. Therefore, the research results provide theorical foundation and technical support for the seismic wave explore goaf and abandoned roadway.