GPR Clutter Amplitude Processing to Detect Shallow Geological Targets

Abstract

Abstract:The analysis of clutter in A-scans produced by energy randomly scattered in some specific geological structures, provides information about changes in the shallow sedimentary geology. The A-scans are composed by the coherent energy received from reflections on electromagnetic discontinuities and the incoherent waves from the scattering in small heterogeneities. The reflected waves are attenuated as consequence of absorption, geometrical spreading and losses due to reflections and scattering. Therefore, the amplitude of those waves diminishes and at certain two-way travel times becomes on the same magnitude as the background noise in the radargram, mainly produced by the scattering. The amplitude of the mean background noise is higher when the dispersion of the energy increases. Then, the mean amplitude measured in a properly selected time window is a measurement of the amount of the scattered energy and, therefore, a measurement of the increase of scatterers in the ground. This paper presents a simple processing that allows determining the Mean Amplitude of Incoherent Energy (MAEI) for each A-scan, which is represented in front of the position of the trace. This procedure is tested in a field study, in a city built on a sedimentary basin. The basin is crossed by a large number of hidden subterranean streams and paleochannels. The sedimentary structures due to alluvial deposits produce an amount of the random backscattering of the energy that is measured in a time window. The results are compared along the entire radar line, allowing the location of streams and paleochannels. Numerical models were also used in order to compare the synthetic traces with the field radargrams and to test the proposed processing methodology. The results underscore the amount of the MAEI over the streams and also the existence of a surrounding zone where the amplitude is increasing from the average value to the maximum obtained over the structure. Simulations show that this zone does not correspond to any particular geological change but is consequence of the path of the antenna that receives the scattered energy before arriving to the alluvial deposits.

Lab Non Destructive Test to Analyze the Effect of Corrosion on Ground Penetrating Radar Scans

“…Corrosion altered the surface, making it more irregular and generating a dispersion of the incident energy. This effect has been observed in different GPR applications (e.g., [36][37][38]). This result points to the possibility of corrosion detection at early stages.…”

A Review of GPR Application on Transport Infrastructures: Troubleshooting and Best Practices

“…Changes in the aggregate size also produces changes in the GPR images, showing a large scattering [310]. This effect has been detected in the ground studies [311,312]. Those inspections require the detection of both surfaces of the wall, as it is important to detect the contact between the ground and the wall.…”

GPR Survey on an Iron Mining Area after the Collapse of the Tailings Dam I at the Córrego do Feijão Mine in Brumadinho-MG, Brazil

“…The GPR technology is quite versatile and has been consolidated since the 1980s. Currently, geoscientists have applied the GPR method in a range of approaches, such as interference mapping [12][13][14][15][16][17][18][19][20][21][22][23], natural resources exploration [24][25][26][27], environmental contamination studies [28][29][30][31], archaeological studies [32][33][34][35][36][37][38], forensic studies [39][40][41], sedimentological studies [42][43][44][45], studies of rivers and lakes [46][47][48], and so forth.…”