Deformation-based Support Design for Static and Dynamic Conditions in Mining
Dr. Peter K. Kaiser, Ph.D, P.Eng., F.EIC, F.CAE
Professor Emeritus, Bharti School of Engineering,
Laurentian University, Sudbury, Canada
Hard rock mines are progressing to great depths and mining companies are planning to develop super-caves, some for depths exceeding 2000 m. As mining and civil tunnelling progresses to deep grounds, mining-induced stresses and stress changes cause rock mass fracturing with static and dynamic impact on ground support. Both can lead to large bulking deformations that are imposed in a static or dynamic manner on the ground control systems.
During this workshop, brittle rock mass failure processes will be reviewed within a framework of support selection for highly stressed ground. Deficiencies in current approaches will be discussed with the intent of pointing the way to more rational support design methods for conditions experiencing mining-induced stress change.
Clearly, excavation-induced seismicity and rockburst problems increase with depth and cannot be prevented. Whereas the seismic risk can be reduced by selecting appropriate mining methods and sequences and by strategically placing developments and infrastructure, the last line of defence always comes from effective static and burst-resistant rock support systems that prevent or minimize damage to excavations and thus enhance workplace safety.
This one-day workshop is intended to stimulate discussion on the above-described engineering challenges. The presentations will cover limitations of standard support design by rock mass ratings, aspects of deformation-based support design, limitations of ground-motion based burst-support design, engineering challenges of strain-bursting ground, methods to control and mitigate seismic risk by use of support to mitigate damage.
The workshop content will largely cover, but in much more detail material presented in keynote lectures by the author between 2013 and to-date, including findings presented at the World Tunnelling Congress and the 50th US Rock Mechanics Symposium in 2015. The dynamic aspects are based on research findings from the Canadian RockburstSupport Handbook (CRBSHB, Kaiser et al. 1996) supplemented with recent developments and experiences as well as a design tool, called BurstSupport, which significantly simplifies the support design task for burst prone ground. Through a mix of lectures, demonstrations, and active discussions with the attendees, the science, the art and practical aspects of support selection will be explored.