The Radar Imaging Technic Reaseach Applied To The Dectection In Defect Of Concrete Structure

As the develop of urbanization and infrastructure, the ground penetrating radar(GPR)has been developing at home and abroad with a high rate of speed as a emergingtechnology in NDT(nondestructive testing) in recent years. GPR has been widely usedin civil engineering,but not in concrete structure.It is mainly because radar image cannot be identificated easily under reinforced interference, which has made theimaging research of GPR become a difficulty.The basic theory of radar electromagnetic field, the reflection and refractionspread rule of the electromagnetic wave in the medium of structure and the workingprinciple of GPR are very important for implementing radar detection work andprocessing radar image. they constitute the core of the radar detection theory; It’s aprecondition to acquire radar image setting an acquisition parameter before radardetection. Understanding and acquisition radar image processing technology is a solidbasic for radar image post-processing and radar imaging technology research.There are differences of electromagnetism in the structure of the void,crack, leakiness,different objects and rebar, therefore, in radar scan images they present differentwaveform characteristics, the images vary. The standar concrete sample was preparedto simulate the different defects in concrete,and also detected by the author with theground penetrating radar(GPR). According to standard component designed in theexperiment, we can analyze corresponding image characteristics of the differentdefects in concrete by consulting the radar images in corresponding positions of thecomponent. The standar concrete sample made in this text can offer the requirementsfor radar detections of different frequency antennas and antenna array,so that we canform a standard map for them and lay a foundation for radar imaging technic reaseachapplied to the dectection in defect of concrete structure.Test results indicate that：Based on the reasonable using of technologies such asmove start time、 background removal、vertical bandpass filter、smoothed gain andliner gain,we can effectively reduce the interference information of radar and get ridof the background noise so that get easier to distinguish radar scan images. Thetechnology of antenna array has more channel antennas,which can take advantage ofhigh depth sounding of lower frequency antenna and high resolution of higherfrequency antenna. The multi-channel antenna array technology will turn to a development direction of radar detection in future.