Characteristic of GPR signatures of pipes and wall

Ground Penetrating Radar (GPR) is capable of mapping subsurface pipelines and archaeological features such as floors and walls. These features may exist in conjunction with other archaeological features, and in such scenarios, it becomes challenging to discern responses of pipes and walls from other targets. This study investigates the effects of some commonly encountered constraints such as inclined scanning trajectory, multiple targets in the vicinity and material variation on GPR responses of pipes and walls. Further, the effects of wall inclination and broken walls are also explored in GPR signatures. Interpretation of such signatures in GPR data for archaeological and geotechnical surveys has been a hallenge. A physical model was created to simulate buried pipes and walls under controlled conditions by maintaining density and moisture content of the soil medium. Presence of PVC pipes, plastered brick and stone walls buried in dry sand have been investigated and major observations have been reported. The inclined scanning trajectory on buried pipes shows a change in curvature of hyperbola like signatures. Inclined transects near the ends of pipes and walls manifests single limb GPR signatures. The orientation of a single limb in inclined transects can help in detecting the ends of a pipe or a wall. The responses of multiple pipes and walls show dependence on separation of targets and foot print of an antenna if the targets are separated horizontally; and on the wavelength of an antenna if they are separated vertically. One can discern stone walls from brick walls by recognizing the diffraction of waves by irregular stones in GPresponses. The signatures of walls differ from pipes with respect to the width of apex and variation in intensity in the limb of a signature.