Application of Air-Coupled Ground Penetrating Radar Based on F-K Filtering and BP Migration in High-Speed Railway Tunnel Detection

Abstract

As the number and length of high-speed railway tunnels increase in China, implicit defects such as insufficient lining thicknesses, voids, and poor compaction have become increasingly common, posing a serious threat to train operation safety. It is, therefore, imperative to conduct a comprehensive census of the defects within the tunnel linings. In response to this problem, this study proposes a high-speed railway tunnel detection method based on vehicle-mounted air-coupled GPR. Building on a forward simulation of air-coupled GPR, the study proposes the F-K filtering and BP migration algorithms based on the practical considerations of random noise and imaging interference from the inherent equipment. Through multi-dimensional quantitative comparisons, these algorithms are shown to improve the spectrum entropy values and instantaneous amplitude ratios by 4.6% and 11.6%; and 120% and 180%, respectively, over the mean and bandpass filtering algorithms, demonstrating their ability to suppress clutter and enhance the internal signal prominence of the lining. The experimental results are consistent with the forward simulation trends, and the verification using the ground-coupled GPR detection confirms that air-coupled GPR can meet the requirements of high-speed railway tunnel lining inspections. A comprehensive GPR detection model is proposed to lay the foundation for a subsequent defect census of high-speed railway tunnels.

Remote Sensing and Environmental Monitoring Analysis of Pigment Migrations in Cave of Altamira’s Prehistoric Paintings

“…To reduce this effect and consider the minimum allowable distance to the rock paintings on the Ceiling, data acquisition was performed at a height depending on the 1.6 GHz central-frequency antenna of 10 cm (Figure 5). This height ensured the maximum possible amount of energy transmitted to the rock mass and reduced the effects of coupling to the air to obtain accurate and high-quality GPR records [89,90]. This antenna configuration provided a penetration depth of up to approximately 50 cm into the Polychrome Layer, while maintaining a high-resolution capability [58,80,81].…”

A Multimodal Research Approach to Assessing the Karst Structural Conditions of the Ceiling of a Cave with Palaeolithic Cave Art Paintings: Polychrome Hall at Altamira Cave (Spain)

“…Several authors have conducted software simulation studies and real measurements of the optimal height of antennas relative to a surface during data collection over the last decades [66][67][68][69][70][71][72][73]. These authors concluded that the best GPR data are obtained when antennas are in contact with the ground or close to the ground.…”

Multi visual images fusion approach for metro tunnel defects based on saliency optimization of pixel level defect image features

“…To solve the problem of defect detection in tunnels, Zhai et al [11] proposed a dual-frequency radar signal time-domain coherence calculation to suppress interference. Lei et al [12] proposed an on-board air-coupled GPR approach for high-speed railroad tunnel detection. Svorc et al [13] utilized infrared video streaming to validate the detection and classification of vehicles.…”