Acoustic modeling of coal-rock interface identification

In order to solve the problem of coal-rock interface identification,based on the acoustic detection method,according to the sonicwave reflection and refractio n at the water-coal interface and coal-rock interface which met the physical properties of the acoustic pres-sure continued and particle velcity continued at the interface,a n acoustic transmission path model was established. In consideration ofthe medium attenuation existed in the transmission of the sonic waves at the interfaces in the medi um,two transmission and reflection echoformulas of the water-coal and coal-rock interfaces were derived when the sonic waves transmitted in the water,coal and rock three medi-ums, and the acoustic model of the path transmission coal-rock identification was established. The model was a nonlinear equation,inclu-ding different medium sound absorption coefficient,characteristic impedance,thickness and acoustic wave frequency and amplitude rati-o modulus. With the establishment on the experiment platform of the coal-rock identification,the hydrophone as the sonic wave transceiv-er made up transmit-receive system and analysis device with the signal generator and oscillograph. The SIMULINK was applied to simulatethe acoustic wave transmit-receive and modeling process,to calibrate the sound absorption coefficient of the medium and to solve th e am-plitude ratio model equation of the acoustic wave transmission and receiving to have the seam thickness and water thickness numerical val-ues and thus the feasibilit y of the model was verified. The analogue simulation showed that the theoretical identification error of the seamthickness was 0. 03 m and the further verified with the site t est would be conducted.