The Simulation Research On Transient Electromagnetic Method And Its Application In Engineering Geology

Reacently, electrical method become a subdiscipline with the most types of methods,themost extensive,and the most adaptable in applied geophysics.Among that the transientelectromagnetic method has the advantages of strong ability through high resistence and smallsource disturbance effect, and also has convenient construction,simple surveying work,highworking efficiency and good geological effect and so on a series of benefits,so this paperfocused on the research of the transient electromagnetic method in application of engineeringgeology.On the analysis of the specific process of the transient electromagnetic method,by usingphysical equivalent circuit,explaining operating principle of the transient electromagneticmethod,and using maxwell’s equations to deduce electromagnetic equations and boundarycondition of transient electromagnetic field.According to the principle of electromagneticinduction,when using this method to explorate, the current and the differences of electricalproperties of rock, orebody in the electromagnetic field play a crucial role.Therefore, thispaper has a detailed list of change and electrical properties of different rocks.The emissionwaveforms of the transient electromagnetic method has an important influence on the resultsof exploration.According to these disadvantages,improving the original circuit, three-phasePWM rectifier circuit take the place of the original three-phase controlled rectifyingcircuit.This can improve the stability of DC current and voltage and power factor.And addfilter capacitance on the inverter part to filter harmonic wave, ensuring the quality of theoutput current waveform so as to improve the accuracy of the measurement. Simulationexperiment in Matlab/Simulink and draw the waveform figure of the transientelectromagnetic method.Dunhua Copper Mining area has good mineral vision.This paper applied transientelectromagnetic method to prediction of the Dunhua Copper Mining area. First to analyzesecondary magnetic of field frequency, time characteristics, through programming in Matlabto draw the corresponding characteristics curve. And then by comparing calculation results ofearly and late apparent resistivity and whole apparent resistivity to get parameter variation ofapparent resistivity of the transient electric magnetic field when mine area change, then drawthe corresponding data conclusion.At last, use Matlab grids function processing data andsimulating the field change of transient electromagnetic field in Dunhuacopper mining area tocomplete the prediction of mining area.From the analysis results,the prediction results of thetransient electromagnetic method are more accurate than using geophysical data. After theimprovement, not only improves the work efficiency, and also improve the accuracy ofprediction.