2−1/2 Dimensional bi-static GPR propagation and scattering modeling of roadways and tunnels with projected 2D FDTD

Subsurface sensing modalities such as Ground Penetrating Radar (GPR) are increasingly being used to assess the condition of aging civil infrastructure by evaluating deterioration within roadways and bridges, and to monitor the security of national borders by the detection of underground tunnels. The need to address these issues is intensifying and, while valuable data are collected using nondestructive evaluation there is urgency for improved understanding and analysis. Simulation of GPR investigations to search for defects in bridges and the presence of underground tunnels can help to understand and analyze real world data. Three-dimensional simulations consider the full geometry of an area. When the geometry is relatively invariant in the third dimension, 2-1/2D simulations can capture most of the 3D scattering and account for bi-static transmitters and receivers located out of the cross-sectional plane. Additionally, comparison of 3D simulation results to a library of 2D results may help to indicate the angle of GPR travel from the cross-sectional plane.