Observation Frequency Selection Based on Dynamic and Electric Field Excitation Method for Advanced Detection in Coal Mine Roadway

The dynamic and electric field excitation method is a new advanced detection method. In this method, the observation frequency and of emission electrode must be reasonably selected according to the actual geological conditions of coal mine roadway to obtain the apparent frequency with adequate Induced Polarization (IP) information of geological anomalies and improve the measurement accuracy of the instrument. This paper completed the simulation of apparent frequency varying with the observation frequency and Cole-Cole model parameters with MATLAB software. The results show that the key to selecting the observation frequency mainly depends on the charge and discharge time constant .Then the paper analyzed the effect of the measured apparent frequency on the measurement accuracy. According to time constant values​​ of geological conditions in coal mine roadway, considering the efficiency and electromagnetic coupling effects on the measurement, it is best to select the observation frequency within a frequency range of 0.05~0.1Hz and the frequency ratio coefficient of 13 or 15. Now apparent IP effect is obtained.