Ground & GPR
Ground penetrating radar was first used in the 1920s on a glacier. (1)However it wasn’t until the 1950s that it was investigated and more applications found and further developments occurred. (1) This occurred after an airplane crash where U. S Air force radars ere seeing through ice as the planes were landing in Greenland. (1) In the 1970s commercial manufacturing began and this set the pace for GPR being used in various different ways. (1) Ground Penetrating radar surveys survey the ground to different depths and can produce an underground crossectional image which can be two dimensional or three dimensional.
(2. ) This is the most reliable and cost effective method. (3) GPR uses electromagnetic waves to image below the ground. The GPR system sends radar pulses which are reflected back from the various subsurface structures and received to produce an image by the devices. . (3) This can take nanoseconds. (4) GPR can be performed from the air, ground, in a hole or via satellite. (1) and can use simple hand held devices to more sophisticated bulky machinery depending on the requirements of the job. GPR equipment is made of a control unit, an antenna and a power supply.
(5) The antenna receives an electrical pulse and transmits it to the ground or other medium at a particular frequency. (5) The higher the frequency the shallower the depth of penetration but it will see smaller targets. (5)Some of the GPR energy is reflected back to the antenna and some is lost. (5) Different frequencies are used for different depths and according to different structures mapped. Appropriate Application Primary Antenna Choice Secondary Antenna Choice Depth Range (Approximate) Structural Concrete, Roadways, Bridge Decks 2600 MHz 1600 MHz 0-0. 3 m (0-1. 0 ft) Structural Concrete, Roadways, Bridge Decks 1600 MHz 1000 MHz 0-0.
45 m (0-1. 5 ft) Structural Concrete, Roadways, Bridge Decks 1000 MHz 900 MHz 0-0. 6 m (0-2. 0 ft) Concrete, Shallow Soils, Archaeology 900 MHz 400 MHz 0-1 m (0-3 ft) Shallow Geology, Utilities, UST’s, Archaeology 400 MHz 270 MHz 0-4 m (0-12 ft) Geology, Environmental, Utility, Archaeology 270 MHz 200 MHz 0-5. 5 m (0-18 ft) Geology, Environmental, Utility, Archaeology 200 MHz 100 MHz 0-9 m (0-25 ft) Geologic Profiling 100 MHz MLF (16-80 MHz) 0-30 m (0-90 ft) Geologic Profiling MLF (16-80 MHz) None Greater than 30 m (90 ft) (5)The table shows different frequency requirements for different materials and different depths.
Shallow ground penetrating radar surveys can be conducted by one person using hand held equipment. . (2. ) This can help locate pipes, tanks, drums, give concrete imaging and help locate unmarked cemeteries and in other archaeological studies. . (2, 6) Deeper ground penetrating surveys ca n be used for landfill and burial trench delineation , geology and bedrock depth studies and karst caves(7) and sinkhole location. . (2) Ground penetrating Radar can be used in locating and mapping infrastructure, civil engineering where it can be used to map a building, bridge or foundation.
. (3)GPR has been used to locate minerals and underground water levels. . (3) GPR can be applied to many fields such as environmental studies, nanotechnology, forensics and archaeology. . (3) There are always new advances and one such company is Geophysical survey systems, Inc. A new cart has been introduced and the Structure Scan Optical 2600 which can reveal objects using low frequency antenna. (8) The software which has progressed has also helped with complicated mapping and imaging that wasn’t possible before. References 1. Olhoeft, G. (2003) Ground Penetrating Radar. 2008 November 15. Available from : http://www.
g-p-r. com/introduc. htm 2. GeoModel Inc. Ground Penetrating radar surveys 2008 November 15. Available from :http://www. geomodel. com/ 3. GeoSense (2007) Ground penetrating Radar Survey Systems. Environmental and engineering Geophysical centre. 2008 November 15. Available from : http://www. geo-sense. com/GPR. htm 4. University of South Hampton (2008) Ground penetrating radar Survey. 2008 November 15. Available from : http://www. southampton. ac. uk/archaeology/research/enterprise_apss_ground. html 5. Geophysical survey systems, Inc. What is GPR. 2008 November 15. Available from : http://www. geophysical. com/WhatIsGPR.
htm 6. GeoModel Inc. Locating Graves. 2008 November 15. Available from :http://www. geomodel. com/graves/ 7. Quarto, R. et al (2006) Ground penetrating radar survey of a prehistoric site in southern Italy, Department of Geology and Geophysics, University of Bari 2008 November 15. Available from :http://www. sciencedirect. com/science? _ob=ArticleURL&_udi=B6WH8-4NM5XXG-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10&md5=10dd3e00d745356427469db3c8d48b96 8. Geophysical survey systems, Inc. Whats New? 2008 November 15. Available from :http://www. geophysical. com/whatsnewatgssi. htmSample Essay of RushEssay.com