Drill process monitoring in percussive drilling for location of structural features, lithological boundaries and rock properties, and for drill productivity evaluation

Abstract: This thesis deals with the application of percussive drill monitoring in the mining and underground construction industries. The technique has been used to provide information on different ground properties and conditions and for drill productivity evaluation. Five different test sites have been used: the OSCAR area in the Kiirunavaara magnetite mine in Kiruna, the Viscaria copper mine in Kiruna, the Zinkgruvan mine in south-central Sweden, the Glödberget tunneling site in Västerbotten county and the Hallandsåsen tunneling site in southern Sweden. A methodology has been suggested and tested for treatment of raw data in order to extract rock dependent parameter variations from variations generated by the drill system itself and other external influences. Prediction of rock hardness and fracturing can be done without initial calibration, providing a good foundation for interpretation by site personnel. The mining applications show that drill monitoring has a very high potential for ore boundary delineation and also for classification of existing rock types. In tunneling applications drill monitoring demonstrates a good capability of foreseeing rock conditions ahead of the tunnel face. Other benefits are the speed of the method, its practicality and the fact that it requires no additional equipment, time or access to the production front. The potential for detailed drill productivity evaluation by drill monitoring has been demonstrated. Detailed information of the time consumption for each activity in the drilling cycle can be presented as well as the distribution of the total production. With this information in hand an indication can be given as to how the overall drilling capacity can be increased. The impact on production of automation, new developments and organization can also be predicted with high accuracy.