Investigation of Rock-fall and Support Damage Induced by Seismic Motion at Kiirunavaara Mine

University essay from LuleƄ/Department of Civil, Environmental and Natural Resources Engineering

Abstract: Damages in rock openings that are related to mining induced seismicity have increasingly become major problems in deep underground mines as mining depths continue advancing in Sweden and in all around the world.
The solution to rockburst problem starts with the understanding of the mechanisms in which rockbursts and the triggering seismic events occur. The seismic source parameters registered and calculated by the seismic monitoring systems installed in mines can be used as tools in the investigation and analysis of damages related to seismicity. A correlation can be created between the source parameters and the kinematic responses of excavations, mainly the peak particle velocity, using theoretical and empirical relationships and applying statistical regression over the collected data set.
Accordingly a parameter correlation has been established that can be used for design and back-analysis purposes, specifically to be used in the Kiirunavaara mine. Damages related to seismicity have been classified using rock and support damage scales. A correlation diagram that shows the magnitude of seismic events with the inflicted rock damage levels and the calculated peak particle velocities is demonstrated. Seismic source mechanisms are suggested with the analysis of the data gathered.
The most obvious discovery is major rock damages, in the damage classes of RDL4 and RDL5, have happened at relatively lower peak particle velocities, in the ranges of 25 mm/s or lower. This will lead to a conclusion that the peak particle velocity by itself cannot indicate the severity of damage. Certain mine blocks in the Kiirunavaara mine exhibit higher seismicity and rockbursts; hence, requiring closer attention in the design of support and production sequencing.