Highly Sensitive Damage Detection of Reinforced Concrete Bridge Slab by 'Time-Variant Deconvolution' of SHF-Band Radar Signal

摘要

In this paper, we focus on Ground Penetrating Radar (GPR) for the monitoring of reinforced concrete (RC) bridge slab. Though GPR method is non-contact and high-speed, damage detection accuracy depends on inspectors' skill. Furthermore, the spatial resolution of the system is not enough considering the millimeter-order thickness of target cracks. In this paper, a new algorithm based on deconvolution with the attenuation effect of concrete, "time-variant deconvolution" is proposed, and the effect of the algorithm and frequency range on damage detection accuracy is discussed by real bridge slab model utilizing higher frequency (SHF-band) radar system. When the algorithm was applied to 1 mm horizontal crack above the rebar, only by time-variant deconvolution at SHF-band, dried crack was detectable by its positive-negative peak of the estimated distribution of reflection coefficient at appropriate depth and crack with water was detected by its clear negative peak.