Robust Subsurface Velocity Change Detection Method with Yakumo Multistatic GPR System

To detect pavement damage of airport taxiway caused by cracks inside layer, we applied a novel method to common midpoint (CMP) dataset obtained by multistatic ground penetrating radar (GPR) system YAKUMO. Thin cracks within asphalt layers cause slight variation to the electromagnetic (EM) signal propagation velocity. The proposed method can show higher-resolution images of velocity changes of two different time set data with a small number of CMP traces. YAKUMO can acquire several parallel distributed CMP datasets at each position while moving the system linearly in real time, which makes it possible to apply this method to large-scale inspections. In this research, we acquired datasets at an airport taxi-way model with artificial damages at several times over a year. The datasets are analyzed with the proposed method to find out how the conditions of pavement changes by pressurization and time course. The results show that the method can detect not only overall change but also local area changes.

1. INTRODUCTION

Ground penetrating radar (GPR) is widely used for subsurface exploration. It is a non-destructive method and can obtain higher resolution images than other subsurface imaging method. Other than conventional subsurface imaging using the reflected signals from scatterers, GPR can also be used to estimate the distribution of propagation velocity of electromagnetic waves in subsurface structure. Previous studies show that common midpoint (CMP) velocities can be used for civil engineering applications, hydrogeological applications, and groundwater research [1]. Also, there are many kinds of research on road or pavement inspection targeting distortion or voids beyond the pavement layer [2] [3].