Laser scanning of overbreak anddeformation for crosscuts at Malmbergetmine

Abstract: Nowadays, new measurement technologies are being used in underground mining operationsto increase the safety factors and solve several mining challenges to save time and improve theeffectiveness of mining operations. One of the new tools is the uGPS Rapid Mapper, which hasrecently entered the market. LKAB is one of the companies looking to use modern technologyto help solve problems in its Kiirunavaara and Malmberget underground mines. The operatingmechanism of the uGPS Rapid Mapper was studied and some investigations were carried outwith the device.The first part of this thesis studied the repeatability and accuracy of the uGPS Rapid Mapper™System during actual use. A number of tests were completed and data analysis viaCloudCompare software was carried out. The result of these tests showed that the uGPS RapidMapper is an efficient device that can be counted on for future work with higher reliability interms of output results.The second part of this thesis determined the overbreak percentage caused by blasting and otherfactors. The uGPS Rapid Mapper was used to scan different parts of the mine (areas that havebeen developed more than three months ago and newly-developed areas). The percentageoverbreak that occurred in these selected areas in the mine and the cause of the overbreak wereanalysed. The study indicated that the data collected by uGPS and analyzed using theDeswik.CAD (Reconciliation Tool) is a very effective method for calculating the overbreak.Most of the study areas in this study however showed an overbreak percentage of more than16% with a varying form of percentage overbreak. The potential causes of this variation are asa result of geological structures or more pronounced mining activities, or operations such asdrilling and blasting, scaling, charging and explosives parameters. The results also clearlyindicated that underground deformation, rock support installation, especially the application ofshotcrete plays a major role in filling the void after rock falls and reducing geometric crosscutentry size.The final part of the work investigated the deformation that occurred in some parts of the minewhere it is believed to have deformations exceeding 20 cm. These parts of the mine werescanned regularly for four months, and the data were analysed using CloudCompare andDeswik.CAD software. The result of the deformation studies showed that the uGPS RapidiiMapper can effectively recognize the changes underground where the recorded deformationhas exceeded 40 cm.The results confirmed that the uGPS Rapid Mapper can be used to effectively monitorunderground changes in the mine through regular underground scanning and analysis of thescanned data.