2d Gpr Data Analysis of Concrete Structures Using Migration Velocity Simulation Algorithm

Ground Penetrating Radar is becoming increasingly popular to use as a non-destructive assessment method for investigating reinforced concrete structures. The large amount of data collected take significant level of experience to interpret. Ground Penetrating Radar scans of concrete produce images which are made of arc segments. The shape of each arc is determined by the shape of the object, position, the dielectric properties and structure of the medium and the path of the radar beam. Current algorithms to calculate the depth of the buried targets utilise a ‘trial and error’ type approach to determine the propagation velocity throughout the concrete structure. The GPR image is migrated for a range of velocities in order to determine the velocity at which the characteristic hyperbola best focuses to a point indicating the propagation velocity in the ground. When this velocity is known, the voltage-distance-time relationship is used to calculate pipe depth. Simulating migration algorithms can use the velocity profile to migrate at specific velocities, hence decreasing the computation time required. After migration, depth information can be read off the migrated image. The results of this work on a concrete sample shows that ground penetrating radar can be used to calculate the depth and position of buried pipes, rebar and cables. The simulated results from the algorithm used are compared and verified with the experimental data from the concrete sample.