Title: Assessment of rock mass quality using drill monitoring technique for hydraulic ITH drills

Authors: Rajib Ghosh; Markus Danielsson; Anna Gustafson; Hanna Falksund; Håkan Schunnesson

Addresses: Division of Mining and Geotechnical Engineering, Luleå University of Technology, Luleå, 971 87, Sweden ' Division of Mining and Geotechnical Engineering, Luleå University of Technology, Luleå, 971 87, Sweden ' Division of Mining and Geotechnical Engineering, Luleå University of Technology, Luleå, 971 87, Sweden ' Luossavaara-Kiirunavaara Aktiebolag (LKAB), Malmberget, 983 31, Sweden ' Division of Mining and Geotechnical Engineering, Luleå University of Technology, Luleå, 971 87, Sweden

Abstract: A rock drilling system always responds to variations in the mechanical properties of the penetrated rock mass. Combining the drill response with a detailed understanding of the drill system has the potential to give a detailed and high-resolution characterisation of the penetrated rock mass along the borehole. This paper analyses 186 boreholes, drilled using a water powered in-the-hole (ITH) drilling technique considering drill parameters; penetration rate, rotation pressure, feed pressure and percussive pressure. In addition, it suggests, calculates and uses a parameter reflecting rock fracturing. Sixty-three of the holes were filmed with a borehole camera to reveal the geo-mechanical features. The results show that the responses from the drill monitoring system can distinguish between solid rock, fracture zones, cavities and damaged rock. The ability to extract this information directly from the drilling operation provides unique prior information and can be useful to adjust production planning before charging and blasting boreholes.

Keywords: drill monitoring technique; in-the-hole; ITH; measurement while drilling; MWD; borehole filming; cavity; fracture zones.

DOI: 10.1504/IJMME.2017.085830

International Journal of Mining and Mineral Engineering, 2017 Vol.8 No.3, pp.169 - 186

Received: 13 Oct 2016
Accepted: 15 Jan 2017
Published online: 15 Aug 2017 *

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