Ground Penetrating Radar (GPR) or Georadar is a non destructive technique. The system is based on the study of the reflections of high frequency electromagnetic radiation.

 

FUNDAMENTAL THEORY

A GPR system is composed of a transmitter and receiver connected to a pair of antenna that sit on the ground surface. The transmitted signal, with a frequency that oscillates between 16 and 2000 Mhz, penetrates the ground and a reflection (depending on the materials through which it has travelled, and the material which produces the reflection) is returned. Reflected signals from a buried object are detected by the receiver antenna, calculating the time of arrival.

To construct an image that the operator can interpret, the data is represented as an image section of the reflected radiation, with time (proportional to depth) vertical and offset distance displayed horizontally. This is displayed on a screen in the field, or can be transferred to a computer and viewed/ edited in the office.

 

DEPTH OF INVESTIGATION

The two factors that affect the depth of investigation are determined by instrument limitations and the geology of the area. The depth of penetration of GPR decreases in areas with elevated ground conductivity (high with content of clays and other fine sediments and particularly high with when water is present).

The depth of investigation increases when using transmitter antennas with lower frequency.

 

ADVANTAGES OF GPR

GPR is the modern method with most success, in non-invasive investigations of subsurface, without necessity to excavate or other destructive interference, it is therefore a method does not affect the environment. It is excellent for the phases of planning and management of industrial projects. Additionally, as it does not require physical contact with the ground (electrodes…) it is rapid and easy in its application in all environments.

 

APLICATIONS

•Archaeology and palaeontology: definition of zones of excavation in archaeological or palaeontological deposits. Location of buried paths, burial sites, walls and fossils.

•Investigation in ice mass and glaciers (thickness, presence of cracks, etc.)

•Police investigations: search for illegal burials, tunnels, bunkers, etc.

 

TYPE OF WORK REALIZED

• Detection of buried services for trenching of ONO, JAZZTEL and TELEFONICA of more than 400000m

• Detection of buried services for trenching of GAS of more 200.000 m

• Detection of footings of bridges

• Placement of boreholes in urban areas

• Determination of cavities

• Slope stability studies

• Studies of cement degradation

• Detection and mapping of tubes

• Archaeological characterisation through geo-radar

• Geophysical studies for placement of directed horizontal perforations

• Studies of glaciers

• Studies of terrain for placements of large works (airports, power stations, urbanisations,..)

• Detection of galleries and passages in archaeological investigations and buildings