Radar systems for tomographic bridge deck inspection

摘要

The development of ground-penetrating radar bridge deck inspection systems sponsored by the Federal Highway Administration is presented. Two radar systems have been designed and built by lawrence Livermore National Laboratory. The HERMES bridge inspector (High-speed Electromagnetic Roadway Mapping and Evaluation System) is housed in a trailer and designed to survey the deck condition during normal traffic flow. Thus the need for traffic control during inspection is eliminated. This system employs a 64 channel antenna array covering 1.9 m in width with a sampling density of 3 cm. To investigate particular areas of a bridge deck in more detail a slower, cart mounted radar has been produced. Thi system is named PERES (Precision Electromagnetic Roadway Evaluation System). The density of data coverage with PERES is 1 cm and an average of 100 samples is taken at each location to improve the signal to noise ratio. Images of the deck interior are reconstructed from the original data using synthetic aperture tomography. The objective of these systems is the determination of unknown structural dimensions and location of defects. The targets include asphalt/concrete thickness, steel reinforcement bars, corrosion related delaminations, voids and disbonds.