Experimental Study of Electrical Resistivity to Rock Fracture Intensity and Aperture Size

Amadu Casmed Charles^1, , Gawu Simon K.Y² and Abanyie K. Samuel¹

¹Earth and Environmental Sciences Department, University for Development Studies (UDS), P. O. Box 20, Navrongo, Ghana

²Department of Geological Engineering, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana

Cite this paper:
Amadu Casmed Charles, Gawu Simon K.Y and Abanyie K. Samuel. Experimental Study of Electrical Resistivity to Rock Fracture Intensity and Aperture Size. International Journal of Physics. 2018; 6(3):85-92. doi: 10.12691/ijp-6-3-4

Abstract

Fracture geometric characteristics (FGC) such as fracture intensity, fracture network connectivity and aperture distribution are crucial features controlling the hydraulic and geotechnical properties of rock formations. Geophysical methods have been used to detect contrast in subsurface material. The Electrical Resistivity (ER) method is one of such methods. The method was applied in an experimental test to investigate ER response with varying fracture intensity I_f and aperture size Aper width in an experimental set-up at Kwame Nkrumah University of Science and Technology (KNUST, Kumasi, Ghana, geotechnical laboratory. The concepts of electrical resistivity variation with rock mass fracture intensity, and aperture were used to obtained experimental data. ER profiles, each measuring 0.9 m long were recorded using 4 electrodes deployed using the Dipole-dipole, Wenner and Schlumberger configurations from the experimental setup. To quantify the relationship between apparent resistivity and fracture intensity, scatter-plots were drawn with apparent resistivity as the abscissa and fracture intensity as well as aperture width as ordinate. There were strong positive linear and regressive correlations between ¦Ña and fracture intensity. Mathematical relationships are established that relate the ER and fracture intensity, and ER with aperture width. The highest coefficient of determination R² of 0.924 was represented for best fit equation, for relationship between apparent resistivity and fracture intensity. For aperture width, the best fit model was given a logarithmic relation as ¦Ñ_a =-465.46(Aperture width)² +4880.5(Aperture width)+1295.5. The study demonstrates the potential usefulness of the ER approach in rock fracture characterisation investigations, which is economic, efficient and less time consuming compared to other methods, of subsurface fracture characterization such core drilling.

Keywords:
geophysics rock block samples rock fracture intensity electrical resistivity experiments

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References:

[1]	Griffin, T. W. and Watson, K. W. (2002). A Comparison of Field Techniques for Confirming Dense Nonaqueous Phase Liquids. Groundwater Monitoring and Remediation, Vol. 22, Issue 2. pp 48-59.
[2]	Reynolds, J. M. (2011). An Introduction to Applied and Environmental Geophysics. New York, NY: Wiley-Blackwell.
[3]	Kumari S, Israil M, Mittal S, Rai J (2009) Soil characterization using electrical resistivity tomography and geotechnical investigations. J Appl Geophys. 67(1): 74-79.
[4]	Piegaria, E., Cataudella, V., Di Maio, R., Milano, L., Nicodemi, M. and Soldovieri, M. G. (2009). Electrical resistivity tomography and statistical analysis in landslide modelling: a conceptual approach. J Appl Geophys 68(2): 151-158.
[5]	Brunet, P., R¨¦mi, C., Christophe, B. (2010). Monitoring soil water content and deficit using electrical resistivity tomography (ERT) ¨C A case study in the cavennes area, France. J Hydrol. 380(1-2): 146-153.
[6]	de Franco, R., Biella, G., Tosi, L., Teatini, P., Lozej, A., Chiozzotto, B., Giada M., Rizzetto, F., Claude, C., Mayer, A., Bassan, V. and Gasparetto-Stori, G. (2009). Monitoring the saltwater intrusion by time lapse electrical resistivity tomography: the chioggia test site (Venice Lagoon, Italy). J Appl Geophys 69(3-4):117-130.
[7]	Boadu, F. K., and Long, L. T. (1996), Effects of fractures on seismic-wave velocity and attenuation. Geophys. J. Int., 127, pp. 86-110.
[8]	Loke, M. H. (2001). Electrical Imaging Surveys for Environmental and Engineering Studies. A Practical Guide to 2-D and 3-D Surveys. RES2DINV Manual. IRIS Instruments. www.iris-intruments.com.
[9]	Skinner, D., Heinson, G., (2004). A comparison of electrical and electromagnetic methods for the detection of hydraulic pathways in a fractured rock aquifer, Clare Valley, South Australia. Hydrogeol. J. 12, 576-590.
[10]	Telford, W. M. W.; Gedart, L. P.; Sheriff, R. E. (1990) Applied Geophysics. London, UK: Cambridge University Press - Second Edition. 792 p.
[11]	Singh, D. N., Kuriyan, S. J., Chakravarthy, M. (2001). A generalized relationship between soil electrical and thermal resistivities. Exp. Thermal Fluid Sci. 25 (3-4), 175-181.
[12]	Lowrie, W. (1997). Fundamental of geophysics, Cambridge University Press, Switzerland, 254 pp.
[13]	¦³sourlos, P. (1995). Modeling, Interpretation and Inversion of Multi-electrode Resistivity Data. D.Phil. Thesis, University of York, 315 pp.
[14]	Everett, M. E. (2013). Near-Surface Applied Geophysics. Cambridge University Press, 442 p.
[15]	Vogelsang, D (1995). Environmental Geophysics: A practical guide. Berlin: Springer.173p.
[16]	Amadu, C. C. Foli, G. and Abanyie, S. (2017). Rock Fracture Characterization for Solid Waste Disposal Site Selection: A Case from Sites in the Accra-Tema Area, SE Ghana. World Journal of Environmental Engineering, Vol. 5, No. 1, 7-16.
[17]	Kesse, G. O. (1985). The mineral and rock resources of Ghana. A. A. Balkema Publishers, The Netherlands, 610p.
[18]	Brace, W. F. (1980). Permeability of crystalline and argillaceous rocks, Int. J. Rock. Mech. Min. Sci. Geomech. Abstr. 17, 241-251.
[19]	Brown, S. R. (1989). Transport of fluid and electric current through a single fracture, J. Geophys. Res., 94, 9429-9438.
[20]	Kearey, P. and Brooks, M. (1991). An Introduction to Geophysical Exploration: Blackwell Scientific. 254 pp.
[21]	Loke, M. H. and Barker, R. D. (1996). Rapid least squares inversion of apparent resistivity pseudosections by a quasi-Newton method. Geophys. Prospect, 44, 131-152.
[22]	Slatera, L., Binley, A., Versteegc, R., Cassiani, G., Birkend, R and Sandberg, S. (2002). A 3D ERT study of solute transport in a large experimental tank. Journal of Applied Geophysics. Volume 49, Issue 4, pp. 211-229.