Geodynamic Safety Center, NorNickel’s Polar Division, Norilsk, Russia:

V. P. Marysyuk, Chief Geotechnical Engineer—Director, Candidate of Engineering Sciences, marysyukvp@nornik.ru
M. P. Sergunin, Head of Department of Geotechnical Supervision of Mining

NorNickel Technical Services, Saint-Petersburg, Russia:
S. V. Kuzmin, Chief Geomechanic, Head of Geomechanics Group, Candidate of Engineering Sciences
I. S. Nevolin, Senior Geomechanic in Geomechanics Group

The accurate analysis and assessment of the rock mass behavior reduce geotechnical risks in deeplevel mining and critical civil engineering. The most wide-spread method of engineering investigation is the core analysis, including core orientation. The acoustic methods (ATV) are unchallengeably advantageous over the conventional core analyses. NorNickel’s Polar Division implements geological surveys using all methods available. The authors compare the spatial locations of rock mass defects determined by the method of acoustic scanning of well walls and by the core orientation analysis. The conclusions are verified using the data of surveys implemented by the two methods in the same well. The authors arrive to a conclusion on the higher reliability of the acoustic scanning as against the core orientation analysis. The ATV method more reliably detects more defects, and the total difference in the number of the detected joints is 36 %. The standard deviation in the number of joints in 5 m-long intervals is on the average 3.42. The calculated values of the global joint system show erroneous determination of location of the main joint system. The range of the accurate location error of the main joint system makes 4° for the dip angle and 27° for the dip azimuth. The ATV method offers more accurate interpretation and detection of induced defects, and eliminates errors of coring depth determination.

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