TY - JOUR
T1 - Penetration Properties of Ground Penetrating Radar Waves through Rebar Grids
AU - Liu, Hai
AU - Lu, Hantao
AU - Lin, Jianying
AU - Han, Feng
AU - Liu, Chao
AU - Cui, Jie
AU - Spencer, Billie F.
N1 - Funding Information:
Manuscript received July 29, 2019; revised December 28, 2019, February 27, 2020, and May 11, 2020; accepted May 13, 2020. Date of publication June 4, 2020; date of current version June 24, 2021. This work was supported in part by the National Key Research and Development Program of China under Grant 2016YFC0802400, in part by the National Natural Science Foundation of China under Grant 41874120, and in part by the Natural Science Foundation of Guangdong Province, China, under Grant 2019A1515011162. (Corresponding authors: Chao Liu; Jie Cui.) Hai Liu, Jianying Lin, Chao Liu, and Jie Cui are with the School of Civil Engineering, Guangzhou University, Guangzhou 510006, China (e-mail: hliu@gzhu.edu.cn; chaoliu@gzhu.edu.cn; jcui@gzhu.edu.cn).
Publisher Copyright:
© 2004-2012 IEEE.
PY - 2021/7
Y1 - 2021/7
N2 - Ground-penetrating radar (GPR) has been widely applied to the nondestructive inspection of concrete structures such as tunnel lining, bridge deck, and retaining wall, which are usually reinforced by steel bars. The scattering of electromagnetic (EM) waves caused by the dense steel rebar embedded in the concrete structures has a severe influence on the penetration capacity of GPR waves. In this letter, the scattering and penetration characteristics of EM waves propagating through rebar net are investigated via both numerical and laboratory experiments, with an aim to select the antenna nominal frequency for a different reinforcement density. The results show that the rebar, which is perpendicular to the polarization direction of GPR waves and has a very small diameter compared with the wavelength, is almost transparent to the impinged GPR waves. The scattering and interaction of GPR waves caused by the rebar that is parallel to the polarization direction result in a shielding effect, which is manifested as a blind band in the low-frequency range in the transmitted spectrum. This result violates the rule of thumb commonly used in the GPR community, i.e., the lower frequency has a deeper GPR penetration depth. In the end, a low cutoff frequency is recommended for selecting a GPR antenna with an appropriate nominal frequency when it is used in the detection of an anomaly inside and behind a reinforced concrete structure, in which the spacing of the rebar net is known.
AB - Ground-penetrating radar (GPR) has been widely applied to the nondestructive inspection of concrete structures such as tunnel lining, bridge deck, and retaining wall, which are usually reinforced by steel bars. The scattering of electromagnetic (EM) waves caused by the dense steel rebar embedded in the concrete structures has a severe influence on the penetration capacity of GPR waves. In this letter, the scattering and penetration characteristics of EM waves propagating through rebar net are investigated via both numerical and laboratory experiments, with an aim to select the antenna nominal frequency for a different reinforcement density. The results show that the rebar, which is perpendicular to the polarization direction of GPR waves and has a very small diameter compared with the wavelength, is almost transparent to the impinged GPR waves. The scattering and interaction of GPR waves caused by the rebar that is parallel to the polarization direction result in a shielding effect, which is manifested as a blind band in the low-frequency range in the transmitted spectrum. This result violates the rule of thumb commonly used in the GPR community, i.e., the lower frequency has a deeper GPR penetration depth. In the end, a low cutoff frequency is recommended for selecting a GPR antenna with an appropriate nominal frequency when it is used in the detection of an anomaly inside and behind a reinforced concrete structure, in which the spacing of the rebar net is known.
KW - Attenuation
KW - Ground penetrating radar (GPR)
KW - Penetration depth
KW - Rebar scattering
UR - http://www.scopus.com/inward/record.url?scp=85099074605&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85099074605&partnerID=8YFLogxK
U2 - 10.1109/LGRS.2020.2995670
DO - 10.1109/LGRS.2020.2995670
M3 - Article
AN - SCOPUS:85099074605
SN - 1545-598X
VL - 18
SP - 1199
EP - 1203
JO - IEEE Geoscience and Remote Sensing Letters
JF - IEEE Geoscience and Remote Sensing Letters
IS - 7
M1 - 9108531
ER -