CEMI (the Centre for Excellence in Mining Innovation), working with Golder Associates and SRK Consulting, recently hosted workshops in Sudbury and Toronto on the topic of Structural Geology Guidelines for Use in Burst-prone Underground Mines. The workshops focused on aiding the mining industry to identify and characterize Fault Slip potential. Assessing whether faults will slip is a major concern for deep mining. Un-expected movement induced by mining extraction can, in the worst situations, lead to rock bursts, which can have major adverse impacts.

Now, having available DD’s (displacement discontinui-ties) in Examine2D 8.0, a free Rocscience program, gives the mining industry an incredibly useful additional tool to help in the prediction of fault slip and to help design for fault avoidance or fault problem mitigation.

The software can model faults and joints, allowing the user to plot shear displacements and slip and dilation tendencies along these structures. This tool will be very useful to the mining industry for assessing the potential for mobilizing geological structures of major concern to mining. In most of these situations, you don’t need a plastic solution for the intact rock, so Examine2D is quite adequate.

Mining Industry WorkshopOctober 15-16, 18-19, 2012

For example, slip tendency plots and dilation tendency plots allow one to define regions of likely slip or opening. We can use these as guides for which way to mine through a dipping fault, etc.

Examine2D can also be useful in early tunnelling evaluation to look at adverse faults or jointing structure where non-plastic issues are of most importance; it can help evaluation of deep tunnel situations where bursting and spalling can be of most concern.

Displacement contours around deep tunnel near fault.

Mining: Fault SlipInteractionIssues

Examine2D Excercise

In the workshop setting, the techniques of fault type identification from a geological and geomechanics perspective were addressed and fault slip tendency approaches on the stereonet and within Examine2D were explored. Characterization of faults and topics related to back-analyses of palaeostress were also reviewed.

The Workshop

Problem exercises utilizing Examine2D to explore the effects of faulting on mine sequencing, mirroring the analysis results presented in Castro et al., 2009 were introduced to participants.

The ease and effectiveness of the program for undertaking the sort of analysis, shown in the accompanying figures, is a great technical achieve-ment for Rocscience. Working with Brent Corkum, the chief software engineer at Rocscience Inc., to develop the additional tools and, in particular, the new display op-tions, both along discontinuities and within the rockmass, was a great experience for all of us. The pro-cess involved incorporating several concepts and methods common in structural geology circles, but largely unused in classic rock engineering.

One of the great advances with the new code is that it can be easily applied to the analysis of faulted conditions not only for mining or for deep tunnelling projects, but can be applied in any location where the rockmass is essentially behaving elastically. In fact, brittle fault behaviour is the controlling case for most deep competent rock excavation conditions.

The help and assistance of the Rocscience team in delivering a quality program, distributed to all the workshop participants, was highly praised by CEMI and the other contributors. The distribution of this new version with the useful add-ins as a free tool will, without doubt, be a great contribution to furthering understanding of fault slip issues in a mining context.

Workshop attendance was about 75 for Sudbury and 25 for Toronto – filling both venues to capacity.

Trevor G. CarterPrincipal, Golder AssociatesMississauga, Ontario, Canada

ReferenceCastro, L., Carter, T.G. and Lightfoot, N. (2009) Investigating Factors Influencing Fault-Slip in Seismically Active Structures, ROCKENG09: Proceedings of the 3rd CANUS Rock Mechanics Symposium, Toronto, May 2009 (Ed: M.Diederichs and G. Grasselli).

Fault slip tendency is constant far away from excavation.

Fault slip tendency is affected as excavation approaches fault.

AcknowledgementsCEMI (Damien Duff; Benoit Valley) led the initiative for the Workshops.Golder (Trevor Carter and Rob Bewick) and SRK (Wayne Barnett) teamed together to conduct the course.