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Fourth International Conference on Ground Penetrating Radar
- Conference date: 08 Jun 1992 - 13 Jun 1992
- Location: Rovaniemi, Finland
- Published: 08 June 1992
41 - 45 of 45 results
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Three-dimensional ground probing radar
Authors J.K. van Deen and J.W. de FeijterPulse-echo ground radar has been used for several tens of years to detect underground features and objects. Despite the many smaller improvements and innovations in specific fields of application (Daniels, 1989), no dramatic breakthrough in the method has occurred since the original application. Two factors can be held responsible. In the first place, the different developments have generally been focused on specialized applications and, in line with that, often been published only in specialized and application oriented literature. As a consequence, little cross-fertilization has occurred between different fields of development. In the second place there has been insufficient communication between users and those at the forefront of the technological development. Often the development has taken place either in an instrument oriented organization without much regard for the practical applicability, or in an applications oriented organization lacking the technical and physical background for optimal development.
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Geo-radar in tunneling - The radar tunnel
Authors Harald Westerdahl, Rolf Austvik and Fan-Nian KongBetween 75 and 100 kilometres of tunnel are excavated in Norway each year. In many of these tunnelling projects, the contractor is looking for methods to acquire geological information during the excavation process, enabling him to carry out the project safely and in a cost effective manner. Often the contractor would like to know the geological situation ahead of the tunnel front or the rock thickness and quality above the tunnel.
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Radar imagery and bore hol data - a partnership for identifying a rock instabilty problem
Authors Gerald Rupert, David Summers and Alan HopkinsAs part of the expansion program of the Jefferson National Memorial Expansion Memorial in St. Louis, Missouri, the National Park Service contracted an expansion to the associated museum. This required the floor of an existing room of dimensions 18 m by 25 m be lowered an average of 3 m. In order to maximize seating in the theater, it was also necessary to cut the walls of the excavation as close to flush under the existing footings as could be achieved. The memorial and associated museum are located in the downtown portion of St. Louis and are toured by some two million visitors each year. Consequently, the excavation of the proposed facility was to accomplished without the use of conventional blasting techniques. Figures 1 and 2 illustrate the original ground contour and the required final geometry, respectively. It was estimated that approximately 1200 cubic meters of material needed to be removed. The High Pressure Waterjet Laboratory of the University of Missouri-Rolla proposed to accomplish the work by means of innovative techniques, specifically the use of high pressure water jets and rock splitters designed by the Center. The proposal was accepted, a contract signed and work begun.
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Multistatic Radar System - MRS
Authors Peter Ulriksen and Tekniska Hgskolan I LundSingle channel impulse radars have been in operation for several years for ground penetrating surveys. Usually the radar antenna is kept very close to the surface in order to get an efficient coupling to the ground. This is important when the radio wave absorbtion is strong and the desired penetration is deep. In some cases it has been possible to elevate the antenna and still get a good result. Such applications is the airborne measurement of the equivalent water content in the snow cover and the thickness of freshwater ice. The maximum measured impulse radar penetration we have obtained is 575 m which was obtained in glacial ice in Greenland (Jonsson & Ulriksen 1988). A fundamental problem when operating a ground penetrating radar in the frequency range 80-1000 MHz is that the antennas must be electrically small to be physically manageable. Thus the directivity is always poor. For this reason no results with imaging side looking airborne impulse radars have been presented. Such imagery is very desireable since it would mean the advent of the true color airborne radar image.
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Development of a ground penetrating radar system for object detection and classification
Authors Staffan Abrahamson, Dan Axelsson, Bertil Brusmark, Gunnar Stenstrm and Hans StriforsThe system consists of a radar unit an antenna unit, and a 486 computer. The antenna and radar unit were designed by ERA Technology UK. The radar unit contains a transmitter and receivcer. The width of the transmitted pulse is approximately 1 nanosecond and its frequency content covers the band 200 MHz to 2 GHz. The pulse repetition frequency is 250 kHz and the peak power 50 W. Sampling of the received signal is performed in a repetitive mode, which means that only one sample of a waveform is taken for each transmitted pulse.
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