SLOPE STABILITY
Example of one realisation of ( a ) the analysis of the DFN model to identify all blocks to derive conventional kinematic evaluation considering discontinuity strength and ( b ) the 3DPOF analysis of each block ’ s FOS considering discontinuity strength , rock mass strength , and pore pressure .
and the distance to object tool helps analyse and compare data from a previous or historic dataset . The team can then inspect any areas of movement in the walls .
Groundwork now has a versatile system for scanning internal environments and undertaking undercover stockpile surveys , where drone or photogrammetry access would be difficult . They can now accurately measure and calculate stockpile volumes .
Throup said that the scanning workflow is straightforward , depending on field of view and distance . “ Our staff are surprised how quick and easy it is to set up and use , register data and then measure distance to objects to report on deformation .”
Groundwork has considered other applications , such as creation of pit models where a drone flight is restricted , or underground / tunnel scanning projects .
Groundwork says it aspires to be a leading provider in geotechnical support and advice , with efficient and responsive in-house services for clients . Professional development opportunities have been created for personnel to learn new equipment and technology . For Groundwork , the biggest benefit from using Maptek technology is gaining direct access to data that can be used to inform safe extraction practices in quarry and mining projects .
“ Support from Maptek has been excellent . Safety is the biggest driver , so being able to provide advisory services to clients supported by tangible scan data means we are doing our best to ensure everyone goes home safely ,” concluded Throup .
For the future , Groundwork is considering the PointStudio Geotechnical Tools add-on for conducting further geotechnical assessments and managing geotechnical risks in the quarry environment . They are also exploring opportunities to use Maptek Sentry for real-time wall monitoring .
WSP and Rio Tinto Kennecott on discrete fracture network methods
Coming back to the Slope Stability conference , another paper titled “ Using coupled discrete fracture network and limit equilibrium analysis to improve slope design reliability ” was presented by consultancy WSP Canada Inc . along with customer Rio Tinto Kennecott , the world-leading copper mining operation in Utah . The company is planning a major pushback of the North Wall at their Bingham Canyon operation . This pushback , referred to as the Apex project , represents a significant design challenge given the size of the slope ( proposed design height about 1,200 m ), the structural complexity , the varied geology , and a variety of potential failure mechanisms including purely structural , rock mass , and composite structural-rock mass .
Evidence of these failure mechanisms is provided by a large number of historical instabilities that have developed in the pit wall over time . This paper describes the analysis carried out to evaluate the stability of multibench-scale composite failure mechanisms of the North Wall and , in particular , the use of a combined DFN-LE approach .
Slope designs for the North Wall of Rio Tinto ’ s Bingham Canyon Mine were analysed using discrete fracture network ( DFN ) models coupled with limit equilibrium ( LE )
methods . This analysis was conducted to evaluate the stability of multi-bench-scale composite failure mechanisms .
As part of the DFN model validation , a wallscale back-analysis was conducted by developing a DFN of the North Wall , which included deterministic major structures and accounted for domain boundaries . The blocks identified in the FracMan ® DFN code were analysed using a 3D-LE ( 3DPOF ) solution to consider the rock mass component . The objectives of the model were to calibrate the DFN-LE properties for use in predictive stages and to evaluate whether discrete structures had played a role in historical instabilities . Achievement of these objectives was measured by comparing areas of high block failure percentage ( BF %) with areas where historical instabilities had occurred .
Multiple realisations of the wall-scale DFN were generated to simulate block formation behind the slope . Block stability was then analysed using the 3DPOF solution and heat maps of BF % were developed . These heat maps showed a strong correlation between observed slope instabilities and areas of elevated BF %, confirming that the failure mechanisms likely involved a combination of major and intermediate structures and rock mass failure .
The calibration results confirm that the DFN-LE approach can be used to analyse inter-rampscale instabilities in medium to strong ,
Wireless
Remote Monitoring for safer , smarter management of slopes , processing facilities and transport assets .
info @ senceive . com senceive . com
Visit our Booth 10756
Find out more
AUGUST 2024 | International Mining 79