Damage mapping of footwall fracturing at the Kiirunavaara mine : underground mapping between levels 320 and 775 m

• This document contains the results and analyses of a mapping campaign for the partial determination of the outer fracture line in the Kiirunavaara footwall conducted on 19-22 March 2013. As reference the levels 320, 420, 507, 540, 740 and 775 m have been used. Damage mapping has during this campaign been performed on all levels except level 420 m where previous mapping results were considered sufficient. The results from the mapping showed that the outer fracture line has been practically stationary on the shallow levels during the last years as new damage was only observed on the deeper levels. Damage on levels above 740 m was judged to be mainly controlled by naturally existing discontinuities. On levels below 740 m the majority of the failures seemed to be stress induced. The results have been used to interpolate damage lines along the respective levels which have then been used to estimate a continuous fracture surface between the studied levels. The fracture surface was analysed with respect to the geometrical shape and with some consideration to the position of the underground infrastructure. A simplified construction plane of the fracture surface could be stated as dipping 55-60˚ to the east and striking parallel to the ore contact. An extension of the construction plane towards the ground surface indicates a day-lighting line that lies significantly further into the footwall than surface cracks have been observed. Extension of the construction plane downwards was not recommended as the behaviour of the lowest mapped level (775) significantly deviates from the dip and strike indicated by the above lying observations.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Annan samhällsbyggnadsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Other Civil Engineering (hsv//eng)

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Mining and Rock Engineering

Gruv- och Berganläggningsteknik

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