Detection of buried tunnel using 2D numerical simulation of GPR data; a case study: Tunnel No. 3 of Tehran-Pardis Highway

Today, geophysical methods are one of the most feasible means for exploration, detection and localization of underground targets. One of the most used geophysical methods is ground penetration radar (GPR). In this method, based on the depth, shape and electromagnetic properties of the target and surrounding environment, electromagnetic waves with different central frequencies are propagated through the medium. In this paper, first, the theory of GPR, and then, forward modeling of GPR data using finite difference time domain (FDTD) method with consideration of convolutional perfectly matched layer (CPML) absorbing condition are presented. Finally, forward modeling of a buried tunnel in different geological environments is presented and the results are assessed. A schematic model of a tunnel in Tehran-Pardis highway is also constructed and the results of the simulation of the tunnel are compared with the field data.