Forward time domain ground penentrating radar modeling of bridge decks for detecting deterioration

• Online Access: http://hdl.handle.net/2047/d10009322

Ground penetrating radar (GPR) for nondestructive testing is a relatively young technology, especially with application to civil infrastructure such as bridges and roadways. Conventional methods of processing and analyzing GPR data for civil infrastructure are often qualitative, using relative reflection amplitude from subsurface boundaries or reinforcing steel (rebars) as an indicator of health. This poster brings well understood electrical engineering analysis tools to the application of nondestructive testing of bridges using GPR. Using iterative forward modeling to improve upon conventional permittivity and depth calculations, a computational model geometry is computed for the assumed bridge deck with no anomalies present. A Finite Difference Time Domain (FDTD) GPR simulation on this model results in healthy bridge deck data that can be removed from measured data to bring anomalies to attention. For the purpose of this poster, the measured data is also simulated. In lieu of modeling the identified rebars is perfect electrical conductors (PECs), they are modeled as hard point source excitations. This allows for examination of the effect that the scattered waves from the rebar have on an anomaly, which is often neglected when clutter signals from the rebar are computationally modeled and subtracted. This is an important consideration for application of many inversion methods.