APPLICATION OF GROUND PENETRATING RADAR (GPR) TECHNIQUE TO DETECT POSSIBLE HIDDEN GAPS OR VOIDS IN AN AGRICULTURAL LAND, NAG HAMMADI, QENA, EGYPT

The selected area is an agricultural land of approximately 600 m square. The main target of this study is to detect the size and depth of the subsurface voids or gaps (sinkholes) to treat the problem of irrigation water
loss. Sixteen GPR profiles of different lengths were conducted ranging from 32-35 m, with a separation of 1 m width. The interpretation of GPR profiles reveals the locations of the voids in the selected area, and determine the effective ways to deal with these defects. Results showed locations of different color contrasts and high reflections amplitude of the reflected signals, compared to the surrounding soil; also the higher scattering compare to the bed layer in these locations reveals possible voids in the study area. The depths of the possible targets range from 7.0 m to 8.0 m. 3D analysis was performed for the total GPR profiles to confirm the presence of the possible hidden target and the accurate depths of these objects. Four time-slicing at different (two-way travel time) TWTT were selected together with two X-cut and two Y-cut were done to track the possible hidden target. These results were in agreement with the results obtained from the 2D image. Such information reveal the important of Radar technique in handing the geotechnical problems.