1887
Volume 17, Issue 4
  • ISSN: 1569-4445
  • E-ISSN: 1873-0604

Abstract

ABSTRACT

The identification of geological discontinuities such as fractures and faults is fundamental to geotechnical and hydrogeological characterization of rock masses. It is difficult to characterize these discontinuities, even by means of drill cores. Electrical resistivity has been historically employed as an alternative tool for the characterization of discontinuities, and new equipment for data acquisition and modern interpretation techniques have increased this possibility. However, when the characterization of vertical discontinuities is to be carried out in small areas, such as urban zones or for engineering works, traditional surveying may be impracticable, because it requires larger areas for proper acquisition. In these situations, azimuthal electrical resistivity surveying can be a good option, thanks to faster data acquisition and the possibility of reaching greater depths of investigation. There are several types of azimuthal arrays, but comparative analyses of their efficiency are still scarce. The objective of this study is to compare the applicability of several types of azimuthal resistivity surveys to identify vertical discontinuities in rock masses. The study was carried out in the laboratory using a scale model (tank), where boundary conditions could be well‐defined. We tried to replicate the natural conditions of a karstic area in Brazil, known to have hydrogeological and geotechnical problems associated with subvertical discontinuities. The simulations involved a limestone rock mass crosscut by a set of discontinuities with varied apertures. The selected arrays (square, equatorial dipole–dipole, Wenner and Schlumberger) encompassed varied inter‐electrode spacings and three different thicknesses of a saturated isotropic overburden, so as to represent field conditions. The azimuthal resistivity surveys, especially the Wenner array, proved to be promising in order to detect vertical discontinuities. The non‐collinear arrays are preferable when it comes to discerning the depth of investigation (square) and detecting electric anisotropy (equatorial dipole–dipole), despite small azimuthal distortions that were observed in relation to the strike of the discontinuities.

Loading

Article metrics loading...

/content/journals/10.1002/nsg.12047
2019-05-03
2020-05-26
Loading full text...

Full text loading...

References

  1. BarkerR.D.1989. Depth of investigation of collinear symmetrical four‐electrode arrays. Geophysics54, 1031–1037.
    [Google Scholar]
  2. BinleyR.D., ShawB. and Henry‐PoulterS.1996. Flow pathways in porous media: electrical resistance tomography and dye staining image verification. Measurement Science and Technology7, 384–390.
    [Google Scholar]
  3. Boris, M.2005. Azimuthal resistivity to characterize fractures in the Battleford Formation at King site. Master of Science thesis, Saskatchewan University, Saskatoon, Canada, 161 p.
  4. ChandraP.C.2016. Groundwater Geophysics in Hard Rock. CRC Press/Balkema.
    [Google Scholar]
  5. CPRM
    CPRM . 1996. Informações Básicas Para A Gestão Territorial. Estudos Geofísicos Para Abatimento De Solo Da Rua Cuba. Sete Lagoas, MG. CPRM. Projeto Vida. Belo Horizonte. 32 p.
    [Google Scholar]
  6. EdwardsL.S.1977. A modified pseudosection for resistivity and IP. Geophysics42, 1020–1036.
    [Google Scholar]
  7. Everett, M.E.2013. Near‐Surface Applied Geophysics. New York: Cambridge University Press. 442 p.
    [Google Scholar]
  8. FordD. and WilliamsP.2007. Karst Hydrogeology and Geomorphology. John Wiley & Sons, Ltd.
    [Google Scholar]
  9. Galvão, P.H.F.2015. Modelo Hidrogeológico Conceitual De Sete Lagoas (MG) E Implicações Associadas Ao Desenvolvimento Urbano Em Regiões Cársticas. PhD thesis. São Paulo, Brazil: IG, São Paulo University.
    [Google Scholar]
  10. GalvãoP., HalihanT. and HirataR.2015. Evaluating karst geotechnical risk in the urbanized area of Sete Lagoas, Minas Gerais, Brazil. Hydrogeology Journal23 (7), 1499–1513. https://doi.org/10.1007/s10040-015-1266-X.
    [Google Scholar]
  11. GoudswaardW.1957. On the effect of the tank wall material in geoelectrical model experiments. Geophysical Prospecting5, 272–281.
    [Google Scholar]
  12. GreenhalghS., WieseT. and MarescotL.2010. Comparison of DC sensitivity patterns for anisotropic and isotropic media. Journal of Applied Geophysics70, 103–112.
    [Google Scholar]
  13. HabberjamG.M.1975. Apparent resistivity anisotropy and strike measurements. Geophysical Prospecting23, 211–247.
    [Google Scholar]
  14. HabberjamG.M.1979. Apparent Resistivity Observations and the Use of Square Array Techniques. Geoexploration Monographs No. 9. Berlin: Geopublication Associate.
    [Google Scholar]
  15. HoekE.2007. Practical rock engineering. RocScience. Available from the publisher at https://www.rocscience.com/assets/resources/learning/hoek/Practical-Rock-Engineering-Full-Text.pdf
  16. KellerG.V. and FrischknechtF.C.1966. Electrical Methods in Geophysical Prospecting. New York: Pergamon Press.
    [Google Scholar]
  17. LaneJ.W., HaeniF.P. and WatsonM.1995. Use of a square array direct‐current resistivity method to detect fractures in crystalline bedrock in New Hampshire. Ground Water33, 476–485.
    [Google Scholar]
  18. LokeM.H.1999. Electrical imaging surveys for environmental and engineering studies-a practical guide to 2‐D and 3‐D surveys. Course Notes. Malaysia. 63 p.
  19. LulingM.G.2013. The paradox of anisotropy in electric logging: a simple proof and extensions to other physics domains. Geophysics28, 1–8.
    [Google Scholar]
  20. MatiasM.J.S.2002. Square array anisotropy measurements and resistivity sounding interpretation. Journal of Applied Geophysics49, 185–194.
    [Google Scholar]
  21. MilsomJ. and Eriksen, A.2011. Field Geophysics. 4th ed. Chichester: John Wiley & Sons, Ltd. 304 p.
    [Google Scholar]
  22. OliveiraD.V.2018. Caracterização geofísica e estrutural de área cárstica na cidade de Sete Lagoas – MG com subsídio para estudo geotécnico. MSc dissertation, Federal University of Ouro Preto. Ouro Preto, Brazil.
  23. OrellanaE.1972. Prospección Geoeléctrica En Corriente Continua. 1ED Paraninfo. Madrid: Biblioteca Técnica Philips. 523 p.
    [Google Scholar]
  24. PergavoE., MousatovA. and ShevninV.2001. Joint influence of resistivity anisotropy and inhomogeneity for a single dipping interface between isotropic overburden and anisotropic basement. Symposium on the Application of Geophysics to Environmental and Engineering Problems, Denver, CO. P002, pp 1–10.
  25. PowersC.J., SinghaK. and HaeniF.P.1999. Integration of surface geophysical methods for fracture detection in bedrock at Mirror Lake, New Hampshire. USGS Water‐Resources Investigations Report 99‐4018C3, 757–768.
    [Google Scholar]
  26. RoyA and ApparaoA. 1971. Depth of investigation in direct current methods. Geophysics36, 943–959.
    [Google Scholar]
  27. SinghalB.B.S and GuptaR.P.2010. Applied Hydrogeology of Fractured Rocks, New York: Springer.
    [Google Scholar]
  28. SteinichB and MarinL.E.1997. Determination of flow characteristics in the aquifer of the northwestern peninsular of Yucatan, Mexico. Journal of Hydrology191, 315–331.
    [Google Scholar]
  29. SzalaiS., Novak, A. and SzarkaL.2007. Depth of investigation of dipole‐dipole, non‐collinear and focused geoelectric arrays. Near Surface. 13th European Meeting of Environmental and Engineering Geophysics, Istanbul, Turkey, September 3–5, 2007.
  30. SzalaiS., NovakA. and SzarkaL.2009. Depth of investigation and vertical resolution of surface geoelectric arrays. Journal of Environmental and Engineering Geophysics14, 15–23.
    [Google Scholar]
  31. TaylorR.W. and FlemingA.H.1988. Characterizing jointed systems by azimuthal resistivity surveys. Ground Water26, 464–474.
    [Google Scholar]
  32. WatsonK.A. and BarkerR.D.2010. Tank modeling of azimuthal resistivity surveys over anisotropic bedrock with dipping overburden. Near Surface Geophysics8, 297–309.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journals/10.1002/nsg.12047
Loading
/content/journals/10.1002/nsg.12047
Loading

Data & Media loading...

  • Article Type: Research Article
Keyword(s): Fracture , Modelling , Resistivity and Site characterization
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error