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Geophysical Exploration RNDr. Robert Votoček, RNDr. Jiří Nedvěd.
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Geophysical ExplorationRNDr. Robert Votoček, RNDr. Jiří Nedvěd
The application of geophysical methods to the problems of engineering, geological and hydrogeological investigation enjoy a long-standing in our practice. The first work of this kind was carried out in 1946. The SG-Geotechnika has had its own equipment and experts for geophysical wall loggin since 1970. • The geophysics allows us to extrapolate the data obtained from boreholes, galleries and tests for more accurate interpretation.
Complex of used method depends on solved problematics and includes followings methods: • Geoelectric • Seismic • Georadar • Geomagnetic • Termometric • TV probe in borehole • Special underground methods (tunnels, galleries, caverns)
Optimal choose of methods, procedures and range of works, which are necessary for fulfilment of Your requirements, are applied mainly in followings branches: • Geotechnics • Environment • Hydrogeology • Building industry • Investigation of mineral raw material deposits • Archaeology
Hydrogeology • resource searching, borehole and new well localisation • water development • We qurantee followings usefull data by geophysical measuring: • saturated and faulted zones course • quartenary sediments and weathering cover thickness • thickness and area of sandy collector in clay sediments • bedrock depth–supporting horizon course • ground water depth and direction of move • efficiency of waterproof measures in the surface and underground objects andpipelinecistern • technical condition of boreholes (perforation)
In situ measuring by plant RS-100 M Resistar – multi electrode cable system
Geotechnics, Engineer geology • foundations soils investigation • line buildings investigation (highways, roads, railways,pipelines) • undergound buildings and dams investigation • slope stability investigation • We qurantee followings usefull data by geophysical measuring: • geological characteristic of the territory (rock types, depth and degree of weathered area, faulted zones) • physical and mechanical properties of foundations soils (massif anizotropy, strength and deformation characteristics, rocks rippability and excavation) • compaction fillings control • slope stability (plane and spatial estimation of slope deformations) • forecast of natural arch formation of caverns and galleries, stability of building hole walls, documentation galleries and feeders • cable and pipeline route location • presence and size nonregistered voids, caverns, old mines • pyrotechnicinvestigation • TV borehole viewing (cavern direction and slope)
Geotechnics, Engineer geology In situ measuring refraction survey (SRR), plant Geode-24, co.Geometrics Ltd.-USA
Georadar measuring in boreholes in tomographic mode, SIR-20 (GSSI) plant
Example of georadar tomography – data distribution of relative permittivity
Environment • discovering of contamination rate and size • rock environment clearance • borehole positioning • We qurantee followings usefull data by geophysical and geochemical measuring: • thickness and character of sand sediments • depth of weathering area and relief uderlaing rocks • ground water move direction • soil contamination area • water aggressivity, corrodibility, erratic flows presence • waterproof measure efficiency of surface and underground objects, borehole and pipeline cistern tightness • technical condition of boreholes (perforation)
Environment corrosion measuring – magnitude, direction and density of stray earth currents
Building industry, investigation of mineral raw material deposits, archaeology • identification of structure and tectonic properties • rocks elastic properties determination • strength and rippability of rocks • monitoring and determining of environment corrosion degree • pyrotechnic investigation • layers direction and slope determinaton in boreholes • land radon index measuring for planning permission and buildings acceptance certificate • surface and shallow undersurface temperature measuring • building constructions and line buildings diagnosis
Whole results of geophysical measuring above undermining area
Georadar measuring interpretation, Charles bridge, pile n. 7
Seismic tomoraphy, Charles bridge, pile n.7 – seismic velocity isolines
Interpretation of georadar measuring, Vltava river bed contour lines and point anomaly
Georadar measuring on railway, pulseEKKO 1000 (Sensors&software)
Example of the interpretation and data handling of radar data in form of the deep cut, roadway I/37.
Deformation of road subgrade layer on road I/26 detected by georadar measuring
3-dimensional view of georadar data, Kutná Hora, archaeology investigation
Dipole electromagnetic profiling DEMP, plant DIKO (EM – 31), Geofyzika Brno