Road foundation detailing using ground penetrating radar systems with different frequencies

This paper reports on the assessment of the underground construction details of a road pavement using different frequency ground penetrating radar (GPR) antenna systems. In addition to this, the possible presence and location of an underground watercourse was investigated in this work. The existence of the latter problem was perceived due to reoccurrence of longitudinal and traversal road surface cracking as well as subsidence at a particular location of the road. Reoccurrence of this damage was interpreted and related to the possible existence of an underground watercourse. The original design and the construction of the road were as such to prevent this movement. Therefore it seemed necessary to perform a GPR survey to investigate and confirm the underground construction details of the road. To this purpose, the identified area was surveyed using high to low frequency antennas with 2000 MHz, 900 MHz, 600 MHz and 200 MHz central frequencies of investigation. The results were conclusive in terms of construction details provided and evidence of subsidence within the road identified. The maximum depth of penetration achieved by the use of the 600 MHz and the 200 MHz antennas (maximum of 3 m) did not allow to identify or confirm the existence of any underground watercourse.