Background clutter analysis of GPR signal for sedimentary deposit in Urban Infrastructure

Abstract

Soil site studies are crucial in the analysis of seismic hazard in populated areas. Enhancing the analysis of local seismic behaviour studies is based on the understanding of changes in ground materials of the shallow geology. Ground Penetrating Radar (GPR) is used in this study as a non-destructive geophysical method to understand the characterisation of changes in ground material in the sedimentary deposit due seasonal changes of water content in shallow geology of Sant Pau urban area in Barcelona city. The general objective of this research study is focused on enhancing the local seismic soil site analysis. This study employs GPR images to explore changes in the ground materials that can be associated to changes on the seismic soil response. Research procedure is based on real radar images acquired using 25 MHz centre frequency antenna along two different direction (parallel and perpendicular) of the coastline of the Mediterranean Sea of Barcelona city.Radar images are processed using common post-processing techniques, followed by more specific innovative post-processing methodology to support radar images as a complementary approach. A novel comparative study based on Fast Fourier Transform (FFT) is proposed to investigate the background clutter analysis of GPR signal considering background amplitude and centre of frequency to analyse water content in sedimentary deposit. This approach is developed to enhance the quality of GPR images to detect changes in ground materials by an innovative methodology of the radar data processing. The obtained results are mapped and compared to the information based on historical maps.