Fracture Imaging in Weathered Granitic Quarries Using GPR Data

We study a granite rock quarry, partially covered by a weathering cap, situated at the State of Bahia (Brazil). The aim was to understand the spatial distribution of fracture surfaces inside the rock and distinguish quickly intact marketable granite areas in order to improve quarry management. To interpret the real data, we use a finite-difference scheme to simulate 2D ground penetrating radar data by solving the damped wave equation. The synthetic GPR sections reveals how a conductive clayey overburden (20 mS/m) masks the real position of the fractures in the granite. The algorithm shows clearly the increase in attenuation with the increase of the frequency, and also with the thickness increase of the weathering cover; which is also responsible for the pull-down effect on reflectors below. The results of the modeling have a good agreement with the actual data.