Gpr application
- 1. SEMINAR ON APPLICATION OF GPR GUIDED BY: Prof; . A.BALASUBRAMANIAN DOS in Earth Science MANASAGANGOTHRI PRESENTED BY: VINAY . C M . Sc Geology DOS in Earth Science
- 2. Introduction Application of GPR ENVIRONMENTAL & ARCHAEOLOGICAL SURVEYS Oil and Gases CIVIL SURVEYS Advantages of GPR Disadvantages of GPR
- 3. Introduction GPR is a geophysical method that uses radar pulses to image the subsurface. This nondestructive method uses electromagnetic radiation in the microwave band of the radio spectrum , and detects the reflected signals from subsurface structure. GPR can have application in a variety of media, including rocks, soils, ice, fresh water, pavements and structures. In the right condition , practitioners can use GPR to detect subsurface objects, changes in material properties, and voids and cracks.
- 4. APPLICATIONS ENVIRONMENTAL & ARCHAEOLOGICAL SURVEYS mapping extent of contaminant plumes determining direction of contaminant migration locating buried storage tanks locating buried artifacts, ruins or treasures delineating boundaries of ancient cemeteries and locating burial plots Mapping gravel and sand deposits, determining depth and quantifying volumes Glacial ice thicknesses - in cold ice bedrock-ice contact can be mapped. Finding rebar or culverts during highway construction. Finding caves or sinkholes.
- 5. Oil & Gas: Location of pipelines, utility lines, water and sewer pipes for gas / oil facility surveys Assessing depth of sediment cover over pipeline river crossings and rights of way Determining depth to bedrock for proposed pipeline rights of way Aerial reconnaissance Survey depths up to 4 meters or more (depending on soil conditions - see chart) GPR can be tied to a GPS to yield precise locations 3-D software allows results to be obtained with x, y and z coordinates
- 6. CIVIL SURVEYS Accurate location of in-slab: structural steel (re-bar) stress cables electrical and communication conduits - including PVC, fiber optics, telephone wiring and other non- ferrous materials water and sewer pipes It is essential to avoid hitting these features when coring or drilling through a concrete slab during construction renovations.
- 7. Advantages of GPR As opposed to other locating techniques that are capable of detecting only metallic or conductive utilities and underground targets, GPR can locate and characterize both metallic and non-metallic subsurface features. It is completely nonintrusive, nondestructive and safe. GPR can be thought of as a Subsurface Imaging System, similar to sonar used for underwater applications. With GPR, surface conditions are not a major factor. Targets can be "seen" beneath reinforced concrete, asphalt, gravel, and most other common surfaces. • High-resolution data in certain cases. • Non-destructive and quiet. • Requires only one or two people for field work. • Fast and economic. • Wide spatial coverage may be obtained, can be towed by a truck.
- 8. Disadvantages of GPR Equipment is expensive. Limited penetration depths. Can be used in only specific sediment-bedrock terrains. Requires trained people for data collection and interpretation. Post-processing of data requires sophisticated computer software Information about dialectric properties must be known in order to convert to wave return times to depths.
- 9. References GG 450,Lecture 19 ,February 26, 2006,Ground Penetrating Radar http://www.joeinfo.com/gpr/antenna.MOV http://www.joeinfo.com/gpr/overview.MOV