Berthelot C.,University of Saskatchewan |
Podborochynski D.,University of Saskatchewan |
Saarenketo T.,Roadscanners Oy |
Marjerison B.,Preservation and Surfacing Saskatchewan |
Prang C.,Infrastructure Preservation City of Saskatoon
Advances in Civil Engineering | Year: 2010
This study was undertaken to evaluate the effect of soil type, moisture content, and the presence of frost on road substructure permittivity. Permittivity sensitivity of typical road soils was characterized in the laboratory to provide baseline dielectric constant values which were compared to field ground penetrating radar (GPR) survey results. Both laboratory devices, the complex dielectric network analyzer and the Adek Percometer, as well as the field GPR system were used in this study to measure the dielectric constant of soils. All three systems differentiated between coarse-grained and fine grained soils. In addition, at temperatures below freezing, all three systems identified an increase in water content in soils; however, when frozen, the sensitivity of dielectric constant across soil type and moisture content was significantly reduced. Based on the findings of this study, GPR technology has the ability to characterize in situ substructure soil type and moisture content of typical Saskatchewan road substructure soils. Given the influence of road soil type and moisture content on in-service road performance, this ability could provide road engineers with accurate estimates of in situ structural condition of road structures for preservation and rehabilitation planning and optimization purposes. Copyright 2010 Curtis Berthelot et al.
Kantia P.,Geofcon |
Heikkinen E.,Poyry |
Mustonen S.,Posiva Oy |
Mellanen S.,Genpro Solutions |
And 2 more authors.
Underground - The Way to the Future: Proceedings of the World Tunnel Congress, WTC 2013 | Year: 2013
Preparations for geological disposal of spent nuclear fuel are in progress by Posiva Oy and SKB, who have developed a KBS-3 method for the purpose. Deposition tunnels are excavated using drill and blast method. On tunnel floor, approx. 1.7 (Ø) x 8.7 (h) m wells are bored to accommodate fuel canisters surrounded with bentonite buffer. Excavation will induce a damaged zone (EDZ) in tunnel perimeter and that is considered a major risk for long term safety of disposal as EDZ may constitute a continuous ground water flow path for radio nuclides. Use of Ground Penetrating Radar as a non-destructive method for characterization of EDZ was introduced by Posiva. A 1.5 GHz antenna was addressed into contact with clean, dry rock surfaces to detect changes of electrical resistivity in relation with variation of rock porosity. Electrical resistivity is highly dispersive at high frequencies. This enables use of dispersivity as a measure of EDZ. Computed dispersivity index gives data for EDZ visualization. Task required software development and establishing threshold values of dispersion. Method was verified with sample studies. Measurement is quick and easy to apply. Computed results are standardized. The method confirms relation between extent of fracturing and charge rate and turned out quick, reliable tool for excavation quality control. Method may apply also for tunnel safety monitoring. © 2013 Taylor & Francis Group.
Kantia P.,Posiva Oy |
Heikkinen E.J.,Poyry |
Lehtimaki T.,Swedish Nuclear Fuel and Waste Management Company |
Silvast M.,Roadscanners Oy
Near Surface Geoscience 2012 | Year: 2012
Posiva and SKB are preparing for disposal of spent nuclear fuel deep in the crystalline bedrock. Fuel assemblies are planned to be encapsulated in copper canisters and placed in wells into tunnel floor. Disposal tunnels will be constructed using Drill and Blast method which unavoidably causes EDZ, being one concern in terms of long term safety as it may constitute a hydraulic flow path. As a non destructive and effective method the GPR technique was introduced for EDZ characterization. The GPR EDZ method was tested in several field campaigns in Äspö and in Olkiluoto. High frequency GPR antenna was used in the work on lines parallel to the tunnel. On high frequencies the resistivity is highly dispersive. Detection of the EDZ is based on computing of dispersivity index in a moving window. The EDZ data can be displayed as profiles, maps or volume visualisation. The developed GPR EDZ technique proved to be a quick and effective in locating areas suffering EDZ. The EDZ was indicated to be discontinuous in character. The next stage of method development will use rock sample data and other geophysical methods in verification. Hydraulic conductivity of EDZ volume is also necessary to define.
Roadscanners Oy | Date: 2002-07-23
Roadscanners Oy | Date: 2011-05-26
In the method an existing surface of a bearing course (