Experiment And Method Research On Analyzing Coal Thickness Using Transmission Channel Wave

The change of coal thickness is frequently encountered in the process of coal mining, which causing workingface’s reform, stoping&developing-link affecting the production, even causing casualties and economic losses. Hence, studying the law of coal thickness changes is important to guide the mining design and safety production.Because the channel wave is sensitive to coal thickness changes, and the characteristic of channel wave’s dispersion is obvious which is easy to identify, therefore, channel wave detecting provides an important geophysical exploration methods to solve those problems. Firstly, the linear numerical relationship between the slowness of the channel wave propagation in the coal seam and the thickness of the coal is obtained through numerical simulation in the typical geologic structure of "rock-coal-rock" in a coal seam. The 22204 workingface was experimented with method of channel wave transmission for the change of coal thickness in Guoerzhuang coal mine of Handan coalfield in Hebei provience, China. The 1750 channels data of channel wave’s traveltime was adopted according to the Time-Frequency Analysis which is used to regard the energy envelope extreme point’s time as channel wave’s traveltime, on the basis of this, the travel-time tomography method was used to detect the coal seam’s slowness and the distribution characteristics of coal thickness, and the result was basically consistent with the actual disclosure.Therefore, the channel wave as the propagation of guided wave in coal seam, which can accurately invert coal thickness, and the accuracy of the detection results is ensured by the method of the Time-Frequency Analysis to pick the channel wave’s travel time.