Experimental study on coal seam thickness measurement ofultra-wide band ground penetrating radar

The automatic height adjustment of the shearer drum in the fully mechanized mining face is of great significance for intelligent mining. The traditional coal and rock detection technology cannot take into account the detection depth and detection accuracy simultaneously. The ultra-wideband ground penetrating radar was used to measure the thickness of the coal seam, and the coal-rock interface can be established to realize the automatic height adjustment of the shearer drum. This paper introduced the design of ground penetrating radar device and studied the principle of ground penetrating radar used for coal and rock interface, and reasonably arranged the installation mode of UWB ground penetrating radar in fully mechanized mining face. According to the obvious difference of dielectric constant of coal and rock, the penetrating ability of radar for coal and rock was analyzed, the static and dynamic testing of UWB radar were combined, and the interpretation of static test data through dynamic testing was also strengthened. The data returned by the radar oscilloscope 512 samples per frame was used to complete the waveform display of each frame according to the amplitude of the signal. The resolution of the measurement can reach 4 mm. In order to analyze the boundary position of coal and rock, the collected data was generated into corresponding waveforms. The grayscale image, the depth of the black and white color in the grayscale image reflects the strength of signal. The signal peaks and troughs in the waveform diagram were combined with the radar grayscale map to determine the boundary position of coal and rock, and the thickness of coal seam was calculated. The radar device was equipped with a waterproof environment, dustproof and other harsh envi-ronments. The coal thickness test was carried out in Yujialiang Coal Mine and Wulanmulun Coal Mine of Shendong at the boundary of the coal and rock layers with a certain thickness. The results show that the center frequency for the 5.3～8.8 GHz pulse radar equipped with an antenna with a bandwidth of 0.9～5.0 GHz, the ground penetrating radar has obvious echo characteristics, and the test thickness and actual thickness error can reach 10 mm, which can penetrate the thickness of 2.0 m coal seam. It provides reference for automatic adjustment of coal machine and has certain application value.