Research On 3D Imaging Technology Of Ground Penetrating Radar In Expressway Detection

Ground penetrating radar(GPR)as a geological structure detection scheme has the advantages of nondestructive detection,fast detection and high accuracy.It has been widely used in practical engineering.In the passed field of GPR imaging research,two-dimensional(2D)imaging technology occupies a dominant position in engineering applications.Because 2D imaging technology has its own limitations,three-dimensional(3D)imaging technology can overcome these limitations,and with the development of computer related technologies,3D imaging technology has been developed rapidly.This paper focuses on the research of 3D GPR system,and focuses on the design of 3D GPR system level and migration techniques that can be realized easily in the field of 3D migration imaging.In the study of the system level design of 3D GPR,this paper first gives the basic theorise of GPR,and then combines basic theories and the user needs of the expressway subgrade detection,derives the design index of the hardware system,and then completes the system level design of each subsystem of the GPR.In the design of the hardware system,the design of the main control board of the 3D GPR is mainly studied,including the multi-channel PS-PL data transmission and the Gigabit Ethernet data transmission.In the study of 3D migration imaging technology,in order to get better migration imaging effect,it is necessary to preprocess and process the data of 3D GPR echo data first,and the 3D data processing can be converted into multiple two dimensional data processing.In the data processing part of the host computer,this paper first gives 2D data preprocessing algorithms,including the removal of bad track,zero position correction,gain control and so on,The removal of the bad track is a prerequisite for other data processing.The gain control enhances the echo amplitude of the deep target,making the deep target more easily identified.Secondly,the 2D data processing algorithms,including background elimination,bandpass filtering,wavelet domain filtering,and so on.The background elimination reduces the interference of the standing wave to the target detection at the same location;because the ground penetrating radar echo belongs to the nonstationary signal,so the wavelet domain filtering method is better than the bandpass filter.Finally,we focus on 2D and 3D prestack time migration algorithms that do not require accurate velocity models,which are more suitable for engineering applications.