Analysis of GPR Wave Propagation in Complex Underground Structures Using CUDA-Implemented Conformal FDTD Method

Jianwei Lei,Hongyuan Fang,Zibin Wang,Man Yang,Haitao Wang,Xin Ding,Xiaowang Zhang

doi:10.1155/2019/5043028

Abstract

Ground penetrating radar (GPR), as a kind of fast, effective, and nondestructive tool, has been widely applied to nondestructive testing of road quality. The finite-difference time-domain method (FDTD) is the common numerical method studying the GPR wave propagation law in layered structure. However, the numerical accuracy and computational efficiency are not high because of the Courant-Friedrichs-Lewy (CFL) stability condition. In order to improve the accuracy and efficiency of FDTD simulation model, a parallel conformal FDTD algorithm based on graphics processor unit (GPU) acceleration technology and surface conformal technique was developed. The numerical simulation results showed that CUDA-implemented conformal FDTD method could greatly reduce computational time and the pseudo-waves generated by the ladder approximation. And the efficiency and accuracy of the proposed method are higher than the traditional FDTD method in simulating GPR wave propagation in two-dimensional (2D) complex underground structures.

Highlights

Ground penetrating radar (GPR) is a nondestructive way to detect the internal material distribution of underground structure using electromagnetic waves [1]
finite-difference time-domain method (FDTD) based on the graphics processor unit (GPU) acceleration technique has been applied in the GPR simulation model [35, 36], but the pseudo-waves that are generated by the ladder approximation in FDTD modeling method are not considered
The results showed that the reflection waveform of compute unified device architecture (CUDA)-implemented FDTD method was consistent with the traditional FDTD method, but the CUDA-implemented method reduced the computational time by more than 93.5%

Summary

Introduction

GPR is a nondestructive way to detect the internal material distribution of underground structure using electromagnetic waves [1]. The FDTD method requires large memory and calculation time in simulating GPR wave propagation in 2D complex underground structures due to the limitations of the CFL stability condition [19]. FDTD based on the GPU acceleration technique has been applied in the GPR simulation model [35, 36], but the pseudo-waves that are generated by the ladder approximation in FDTD modeling method are not considered. This study combines FDTD method and surface conformal technique and GPU acceleration technique proposing a precise and efficient forward modeling algorithm of GPR which can greatly reduce computation time and the pseudo-waves that are generated by the ladder approximation. The simulation model of GPR wave propagation in 2D underground structure was established by CUDA-implemented conformal FDTD method. One obtained the simulated reflection waveform from the twolayer pavement model, the other got the simulated GPR trace profile of the pavement model with structural damage, and the last one demonstrated the GPR simulation section of underground structures with voids

FDTD Method

The Simulation of GPR Waves on GPU

Numerical Simulation

32 Medium 1

Findings

Conclusions