Detecting ring separation in masonry arch bridges using GPR: Fid-Bau Portal

Detecting ring separation in masonry arch bridges using GPR

Diamanti, N. / Giannopoulos, A. / Forde, M.C.

Ground penetrating radar (GPR) numerical modelling as well as experimental verification is employed to study the condition of masonry arch bridges in a non-destructive way. The numerical modelling is done using a finite-difference time-domain (FDTD) algorithm. Some initial numerical modelling tests were undertaken using the ADI-FDTD technique. The results show that the use of this method helps to deal with realistic modelling scenarios. This technique overcomes the limitation on the amount of memory that the current computer technology can provide. This technique is unconditionally stable, which means that it does not have the CFL stability condition; hence long simulation times due to the small time-step are no longer required. From the small scale experiments, it is apparent that real data are quite complicated to interpret. Therefore, a complete electromagnetic numerical model is needed to determine parametrically the range of possible ring separation defects that GPR can detect and develop interpretation strategies for GPR data. This model will provide a better understanding of the way electromagnetic waves propagate within the complicated structure of the masonry bridge and consequently deliver preliminary information on the internal bridge structure for applying further investigative methods or repair procedures.