1、Geotechnical Engineering Design in MiningTao Li PhDPrincipal & DirectorTL Geotechnics & MiningTLgmTLgmTL Geotechnics and Mining OutlineGeotechnical Engineering in MiningGeotechnical Engineering in MiningDesign Methodology and CriteriaDesign Methodology and CriteriaMine ExampleMine ExampleCon

2、clusion and SuggestionConclusion and SuggestionTLgmTLgmTL Geotechnics and Mining Comparison between Civil Engineering and Mining Mining Engineering has evolved together with Civil Mining Engineering has evolved together with Civil Engineering (1800 to 1900), although early mining Engineering (1800 t

3、o 1900), although early mining activity was found in Swaziland dated back 4100BC activity was found in Swaziland dated back 4100BC and civil between 4000-2000BCand civil between 4000-2000BCThere are many similarities between civil There are many similarities between civil excavations and mining exca

4、vationsexcavations and mining excavationsMining, in particular bulk mining, has been Mining, in particular bulk mining, has been increasingly larger, deeper and fasterincreasingly larger, deeper and fasterMining environment and materials are more variable Mining environment and materials are more va

5、riable spatially and temporally and often uncertainspatially and temporally and often uncertainCivil Engineering is often a major part in large Civil Engineering is often a major part in large mining project construction, hence civil engineers mining project construction, hence civil engineers emplo

6、yedemployedTLgmTLgmTL Geotechnics and Mining Geotechnical Engineering in MiningIt was established through necessity at mine It was established through necessity at mine sites/projects Mt Isa Mines established sites/projects Mt Isa Mines established first rock mechanics group in 1962-1965first rock m

7、echanics group in 1962-1965The focus has always been on the practical The focus has always been on the practical outcomes: safety, efficiency and innovation outcomes: safety, efficiency and innovation (such as backfill developed at Mt Isa Mines, (such as backfill developed at Mt Isa Mines, most rece

8、ntly Block and Panel Caving by the most recently Block and Panel Caving by the International Caving Study Group)International Caving Study Group)Now, just about all Australian mines, large Now, just about all Australian mines, large or small, pits or underground, have full time or small, pits or und

9、erground, have full time geotechnical engineers and on most project geotechnical engineers and on most project staffstaffTL Geotechnics and Mining TLgmTLgmGeotechnical Engineering in MiningTL Geotechnics and Mining TLgmTLgmGeotechnical Engineering in MiningConcurrently mining SLC above and BC below6

10、mtpa BC1100m below surface and high stress with variable rock mass strengthsExperienced major failures at undercut and partial high hang-ups5100 HF Drive5040 Southern Perimeter drive Open Hole & DHSE LocationsTLgmTLgmTL Geotechnics and Mining Design Methodology and CriteriaTL Geotechnics and Min

11、ing TLgmTLgmCriteriaCriteriaFeasibility (technical and financial)Feasibility (technical and financial)Constructability Constructability OperabilityOperability A design that works in real world - A design that works in real world - minemineUnderground Excavation DesignTL Geotechnics and Mining TLgmTL

12、gmExcavation methods:Excavation methods:Block caving, Panel caving, Sub-Level caving, Block caving, Panel caving, Sub-Level caving, benching, open stoping, Cut&fillbenching, open stoping, Cut&fillExcavation method selection and design Excavation method selection and design objectiveobjective

13、all about getting the mineral/ore out of ground all about getting the mineral/ore out of ground quicker, cheaper and most importantly safelyquicker, cheaper and most importantly safelyExcavation design approachesExcavation design approachesPrecedence, numerical modelling; empirical; Precedence, nume

14、rical modelling; empirical; trial&errortrial&errorObservation Based Design MethodsThe empirical methodsThe empirical methodssuch as Mathews Stability Graphsuch as Mathews Stability GraphThe trial-and-error methods with monitoring and The trial-and-error methods with monitoring and numerical

15、modellingnumerical modellingsuch as trial slope for stater pit in large open such as trial slope for stater pit in large open pits and pits and more recently BC and PC hydro-fracturing more recently BC and PC hydro-fracturing The back-analysis methodsThe back-analysis methodssuch as the “calibrated”

16、 modelling approachsuch as the “calibrated” modelling approach TL Geotechnics and Mining TLgmTLgmRisk and Return Design ApproachThe Risk and Return Approach (Lai 2012) The Risk and Return Approach (Lai 2012) emphasises on both geotechnical engineering emphasises on both geotechnical engineering aspe

17、cts and financial aspects to reach an aspects and financial aspects to reach an optimum deisgn.optimum deisgn.The impacts of most key design parameters and The impacts of most key design parameters and recommendations, such as mining method recommendations, such as mining method selection, sequence

18、and stope dimensions, selection, sequence and stope dimensions, cannot be accurately quantified. cannot be accurately quantified. A risk-based assessment approach is A risk-based assessment approach is increasingly being adopted to examine the increasingly being adopted to examine the designs feasib

19、ility, constructability, and designs feasibility, constructability, and operability operability TL Geotechnics and Mining TLgmTLgmSimultaneousOpen Pit - UG MiningCrown Pillar Failure Mining Induced SeismicityGWLGWL Inrushes Lift 1 Lift 2Abutment Stress Zones Depth 1100 mCave PropagationMajor SlopeIn

20、stabilitiesSubsidence31High In-Situ Stress FieldRock MassCharacterizationBh = 350 mFlRisk Management Considerations: Pit ? Block Cave?A fully integrated geotechnical design process for open pitsTL Geotechnics and Mining TLgmTLgmFrom CSIRO Large From CSIRO Large Pit Design ManualPit Design ManualCadi

21、a Hill Open Pit Steeper SlopesTL Geotechnics and Mining TLgmTLgmGeotechnical Domains, Design Sectors and Slope AnglesInter-ramp angle Inter-ramp angle 56-60 degrees 56-60 degrees and up to 200m and up to 200m height in more height in more competent and competent and less structured less structured d

22、omainsdomainsOther sectors Other sectors inter-ramp angle inter-ramp angle 35-46 degrees up 35-46 degrees up to150m heightto150m heightNorth wall 720m420Northwest wall 560m430West wall 550m520South wall 560m520East wall 580m460TLgmTLgmOptimum Design Must be Supported by Operation Excellence and Tech

23、nologyTL Geotechnics and Mining TLgmTLgmCadia Extended Pit Failure, Designed, Monitored and Video Taped when Occurred TL Geotechnics and Mining TLgmTLgmSimple monitoring and equation can do the trick just as wellTL Geotechnics and Mining TLgmTLgmCompleted mining 625 bench 15/7/04Tf = (T2-T1)2 +T1(2T

24、2 T1-T3)Conclusion and SuggestionGeotechnical engineering design in mining is a Geotechnical engineering design in mining is a “living” process that requires the considerations of “living” process that requires the considerations of the life cycle of a mine in order to deal with the the life cycle of a mine in order to deal with the many variables and uncertaintiesmany variables an