The effect of antenna central frequency and application of advanced processing in locating buried urban utilities by GPR method

Creating new routes for underground cables or intubation, keeping the subsurface utilities and protecting them during the excavation and building requires a thorough knowledge of the exact location of subsurface utilities. Overall good results in GPR closely depends on some factors such as soil type, anomaly properties, survey design and proper selection of antenna. Finally, applying the appropriate processing parameters in accordance with the conditions, soil type and anomaly properties will be out of control and therefore, two other factors i.e. survey design and application of advanced processing parameters will be more important. In survey design, the selection of survey methods such as CMP, 1D or 2D and the appropriate antenna are the main factors influencing the necessary resolution. GPR processing must be performed according to the specific conditions of each study. Since applying appropriate processing parameters can be useful, improper handling can be misleading. In order to locate buried water pipes and telecommunication cables, a GPR survey was applied to Niayesh Tunnel in Tehran. In primary sections, the pipes were not visible appropriately. The most important factor in hardware methods is choosing the correct antenna according to the site conditions and the studied depth. Appropriate processing methods are used in GPR sections as software in order to increase the signal-to-noise ratio for locating the target. According to this issue, we used central frequency shielded antennas (500 MHz, 250 MHz and 100 MHz). Then an advanced processing algorithm including several filters and recorrection parameters was applied. The velocity analysis was done according to the diffraction hyperbola method. In this study, it was attempted to determine the type of the buried anomalies and utilities. However, more research is needed to determine the pipe type of the buried utilities in a GPR survey. Finally, the results of the processing and interpretation of radar data were compared to the real conditions of underground properties. This research will be useful for future GPR work in similar civil excavation projects.