Mine Seismicity and Rockburst Risk Management Project
Mining-induced seismicity and rockbursts
Mining activity results in stress changes in the rock that may, under certain conditions, lead to violent failures taking place in the rock. When rock failure takes place in a violent manner, it radiates waves similar to what happens during an earthquake. These failure events are referred to as mining-induced seismicity, and can be thought of as small earthquakes caused or triggered by the mining stress changes.
Sometimes these seismic events cause damage, in which case the damage associated with the seismic event is referred to as rockbursts.
The ACG’s Mine Seismicity and Rockburst Management Project
Since 1999, the ACG have been involved in research into the mitigation of economic and safety risk associated with seismic risk in hard rock mines. The ACG’s Mine Seismicity and Rockburst Risk Management Project is currently in its 5th phase, with previous phases of the project documented in MERIWA reports M328, M355, M386 and M406. The current phase of the project will conclude in February 2015.
The current project consists of four sub-projects.
Advancing the seismic hazard assessment in mines
This project component aims to develop robust ‘real time’ seismic hazard maps based on recorded seismic data. It further aims to improve the mitigation of the seismic hazard by providing tools for the spatial evaluation of seismic sources.
Quantifying the seismic response to blasting with the aim of providing an improved understanding for re-entry protocols
This subproject aims to develop robust space–time ‘Omori’ decay evaluations of mining-induced seismicity. This will result in improved parameters for the quantification of the spatio–temporal response of the rock mass to the blasting activity, which will lead to improved understanding and more reliable and appropriate re-entry protocols.
Some preliminary results are discussed in the following paper:Woodward, K & Wesseloo, J 2014, ‘An iterative approach to the assessment of the spatial and temporal relationship between seismic responses and blasting’, Proceedings of the 6th South African Rock Engineering Symposium, Southern African Institute of Mining and Metallurgy, Johannesburg, pp. 107-124.
Calibration of dynamic support system design methods
This subproject utilises multivariate statistical analysis on the ACG’s rockburst database in order to obtain an understanding of the influence of different components on the probability of experiencing different rockburst damage levels. This work is an extension and refinement of similar work that has been performed under previous ACG projects.
Verification of analysis techniques for assessing cave geometry and rock mass damage in block caving mines
The monitoring and understanding of the caving process are hampered by the limited access to the rock mass in the cave column. Many caving mines install microseismic monitoring systems, and several procedures have been proposed for using the seismic data to evaluate the caving process and delineate the cave column. These methods, however, lack direct verification. For more detail refer to the following paper:Cumming-Potvin, D & Wesseloo, J 2014, ‘Assessing the state of the rock mass in operating block caving mines: A review’, in R Castro (ed.), Proceedings of the 3rd International Symposium on Block and Sublevel Caving, Universidad de Chile, Santiago, pp. 118-127.
This subproject will perform physical testing in a state-of-the-art geotechnical centrifuge facility at the University of Pretoria to study the caving process and verify some of the methods based on seismic data for the tracking of the cave and evaluation of the rock mass degradation.
Phase Five Project Sponsors
Barrick Gold of Australia
BHP Nickel West
BHP Olympic Dam
Independence Gold (Lightning Nickel)
Perilya Limited, Broken Hill Mine
BCD Resources, Tasmania Mine
Kirkland Lake Gold
MMG Golden Grove
Newmont Asia Pacific
Xstrata Copper EHM Ernest Henry Mine
Xstrata Copper (Kidd Mine)
Xstrata Cosmos Nickel Australia
Xstrata Nickel Rim South Mine Canada