Forward Time Domain Ground Penetrating Radar Modeling of Scattering from Anomalies in the Presence of Steel Reinforcements

Abstract

Ground penetrating radar (GPR) for nondestructive testing is applied to civil infrastructure such as bridges and roadways. Conventional methods of processing and analyzing GPR data for civil infrastructure are often qualitative, using relative reflection amplitude from subsurface boundaries or reinforcing steel (rebars) as an indicator of health. A Finite Difference Time Domain (FDTD) simulation of GPR is used to generate a bridge deck response of a heterogeneous model of a healthy bridge deck. The result is a healthy deck background that can be removed from measured data to bring anomalies to attention. For the purpose of this article, the measured data is also simulated. In lieu of modeling the identified rebars as perfect electrical conductors (PECs), they are modeled as hard point source excitations to allow for examination of the effect that the scattered waves from the rebar can have on an anomaly. This is an important consideration for application of many inversion methods.

A Fluxgate Sensor Application : Coin Identification

“…The features that are important in all sensing methods are low power consumption, low price, being unaffected by environmental changes, high precision, high reliability and stability. Some remote sensing methods used from past to present include electromagnetic induction (EMI) [1][2][3][4][5], ground effect radar (GPR) [6][7][8][9][10][11] and magnetic anomaly [12][13][14][15]18]. Magnetic anomaly is the most widely used remote sensing method due to its low price, low number of equipment and changeable sensitivity.…”

Electromagnetic Waves in Contaminated Soils

“…CWR is more appropriate for deep investigations. For near-surface sensing such as bridge-deck health monitoring, methods such as GPR are more appropriate (Belli et al, 2009 and2009a). GPR studies require addressing the scattering due to the rough soil-air interface in the forward model as well as through the inversion process (Firoozabadi et al, 2007).This chapter describes a numerical modeling approach to Maxwell's equations using a finite difference time domain (FDTD) solution with both monopole and dipole antennae to simulate the scattering and propagation of EM waves in DNAPL-contaminated media.…”