As a shallow geophysical detection technology,Ground Penetrating Radar (GPR) has been widely used in engineering detection.In order to improve the interpretation accuracy of radar data,this paper introduces reverse time migration (RTM) to process and interpret GPR observed data.Firstly,Finite Difference Time Domain (FDTD) equations of electromagnetic wave in two-dimensional TM mode,CFL numerical stability condition and dispersion relations are derived from Maxwell equations.On such a basis,the principle of RTM and the formula of zero time imaging condition are elaborated,and the corresponding program of RTM is compiled.Two typical voids models are established.The simulated data of two typical void GPR models are processed by RTM to verify the validity of GPR RTM in improving imaging resolution.Compared with Kirchhoff migration result,the homing of reflected wave is more accurate and the convergency of diffracted wave is more complete in the RTM image.Finally,RTM is applied to processing the observed data,which is observed on the underground pipeline.The pipeline is accurately delineated,which provides a scientific basis for the follow-up construction and disposal of the road.
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