Impala Platinum Limited Impala Platinum Limited Rock Engineering - - PowerPoint PPT Presentation

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Impala Platinum Limited Impala Platinum Limited Rock Engineering - - PowerPoint PPT Presentation

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Impala Platinum Limited Impala Platinum Limited Rock Engineering Rock Engineering The Application Of The Q- - The Application Of The Q Tunneling Quality I ndex Tunneling Quality I ndex To Rock Mass Assessment To Rock Mass Assessment At I

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SLIDE 1

Impala Platinum Limited Impala Platinum Limited Rock Engineering Rock Engineering

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SLIDE 2

The Application Of The Q The Application Of The Q-

  • Tunneling Quality I ndex

Tunneling Quality I ndex To Rock Mass Assessment To Rock Mass Assessment At I mpala Platinum Mine At I mpala Platinum Mine Wouter Hartman Wouter Hartman Snr Rock Engineer Snr Rock Engineer – – Projects Projects -

  • 2000

2000

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SLIDE 3

1.

  • 1. I ntroduction

I ntroduction 2.

  • 2. Locality Plan

Locality Plan

  • 3. Geological Setting
  • 3. Geological Setting
  • 4. Problem
  • 4. Problem

4.1 FOG Analysis 4.1 FOG Analysis 4.2 Rock Mass Classification Systems 4.2 Rock Mass Classification Systems 4.3 Q 4.3 Q-

  • System Applicability to I mpala

System Applicability to I mpala

  • 6. Conclusions
  • 6. Conclusions
  • 5. Case Studies
  • 5. Case Studies

5.1 Q 5.1 Q-

  • System Methodology

System Methodology 5.2 Q 5.2 Q-

  • I ndex Analysis for 10 Level Crosscut & 23 Level

I ndex Analysis for 10 Level Crosscut & 23 Level Conveyor Conveyor 5.3 Bolt Length Design for permanent mine openings 5.3 Bolt Length Design for permanent mine openings

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SLIDE 4

I ntroduction I ntroduction

Questions remain on how to properly Questions remain on how to properly design support in a quasi design support in a quasi-

  • static

static environment using rock mass environment using rock mass characteristics as an indicator and design characteristics as an indicator and design tool tool

EMPI RI CALLY ? EMPI RI CALLY ?

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SLIDE 5

1.

  • 1. Introduction

Introduction 2.

  • 2. Locality Plan

Locality Plan

  • 3. Geological Setting
  • 3. Geological Setting
  • 4. Problem
  • 4. Problem

4.1 FOG Analysis 4.1 FOG Analysis 4.2 Rock Mass Classification Systems 4.2 Rock Mass Classification Systems 4.3 Q 4.3 Q-

  • System Applicability to Impala

System Applicability to Impala

  • 6. Conclusions
  • 6. Conclusions
  • 5. Case Studies
  • 5. Case Studies

5.1 Q 5.1 Q-

  • System Methodology

System Methodology 5.2 Q 5.2 Q-

  • Index Analysis for 10 Level Crosscut & 23 Level

Index Analysis for 10 Level Crosscut & 23 Level Conveyor Conveyor 5.3 Bolt Length Design for permanent mine openings 5.3 Bolt Length Design for permanent mine openings

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SLIDE 6

Locality Plan Locality Plan

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SLIDE 7

1.

  • 1. Introduction

Introduction 2.

  • 2. Locality Plan

Locality Plan

  • 3. Geological Setting
  • 3. Geological Setting
  • 4. Problem
  • 4. Problem

4.1 FOG Analysis 4.1 FOG Analysis 4.2 Rock Mass Classification Systems 4.2 Rock Mass Classification Systems 4.3 Q 4.3 Q-

  • System Applicability to Impala

System Applicability to Impala

  • 6. Conclusions
  • 6. Conclusions
  • 5. Case Studies
  • 5. Case Studies

5.1 Q 5.1 Q-

  • System Methodology

System Methodology 5.2 Q 5.2 Q-

  • Index Analysis for 10 Level Crosscut & 23 Level

Index Analysis for 10 Level Crosscut & 23 Level Conveyor Conveyor 5.3 Bolt Length Design for permanent mine openings 5.3 Bolt Length Design for permanent mine openings

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SLIDE 8

Geological Setting Geological Setting

Average Thickness (m) Unit Rock Type

34 HW5 Mottled and spotted Anorthosite 3-6 HW4 Spotted Anorthosite (SA) 5-7 HW3 Mottled Anorthosite (MA) 1,5-3 HW2 Spotted Anorthositic Norite 2-6 HW1 Norite 2-3 Bastard Pyroxenite Pyroxenite, Coarse Grained 2-3 M3 Mottled Anorthosite 3-7 M2 Spotted Anorthositic Norite 0,5 M1 Norite 1-1,5 Merensky Pyroxenite Medium to Coarse grain Pyroxenite 0,8 Merensky Reef Chromitite Layer - Pegmatoid 0,4 FW1 Spotted Anorthositic Norite (SAN) 0,2 FW2 Cyclic Unit (Pyroxenite-SAN-MA) 3-5 FW3 Spotted Anorthositic Norite 0,1-0,3 FW4 Mottled Anorthosite 1-3 FW5 Spotted Anorthositic Norite 1-3 FW6 Cyclic Unit (MA-SA-MA) 1-3 FW7 Spotted Anorthositic Norite 0,8-1,2 FW8 Spotted Anorthosite 3-6 FW9 Mottled Anorthosite 3-5 FW10 Spotted Anorthositic Norite 12-15 FW11 Spotted Anorthosite 10-12 FW12 Mottled Anorthosite 5-7 UG2 Pyroxenite with Leader Chromitite Stringers 0,7 UG2 Reef Chromitite 10-12 FW UG2 Pegmatoid 5-7 FW13 Spotted Anorthositic Norite

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SLIDE 9

1.

  • 1. Introduction

Introduction 2.

  • 2. Locality Plan

Locality Plan

  • 3. Geological Setting
  • 3. Geological Setting
  • 4. Problem
  • 4. Problem

4.1 FOG Analysis 4.1 FOG Analysis 4.2 Rock Mass Classification Systems 4.2 Rock Mass Classification Systems 4.3 Q 4.3 Q-

  • System Applicability to I mpala

System Applicability to I mpala

  • 6. Conclusions
  • 6. Conclusions
  • 5. Case Studies
  • 5. Case Studies

5.1 Q 5.1 Q-

  • System Methodology

System Methodology 5.2 Q 5.2 Q-

  • Index Analysis for 10 Level Crosscut & 23 Level

Index Analysis for 10 Level Crosscut & 23 Level Conveyor Conveyor 5.3 Bolt Length Design for permanent mine openings 5.3 Bolt Length Design for permanent mine openings

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SLIDE 10

PROBLEM PROBLEM

  • Support Design Based On Total Fatality Fall Of

Support Design Based On Total Fatality Fall Of Ground 95% Cumulative Analysis Ground 95% Cumulative Analysis

  • When Accident Statistics Are Split I nto Stoping &

When Accident Statistics Are Split I nto Stoping & Development : The Latter Was Found To Be Development : The Latter Was Found To Be Limiting To Properly Design Support Limiting To Properly Design Support

  • Design Development Support Using 50 kN/ m2 Or

Design Development Support Using 50 kN/ m2 Or Use Rock Mass Quality and Excavation Size As Use Rock Mass Quality and Excavation Size As Design Criterion Design Criterion

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SLIDE 11

PROBLEM PROBLEM

FOG FATALI TY ANALYSI S 95% CUMULATI VE FOG FATALI TY ANALYSI S 95% CUMULATI VE -

  • DEVELOPMENT

DEVELOPMENT

1 2 3 4 5 6 7 8 9 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 More THICKNESS FOG's ( metres )

FREQUENCY PLOT 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

CUMULATIVE PERCENTAGE

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SLIDE 12

PROBLEM PROBLEM

FOG FATALI TY ANALYSI S FOG FATALI TY ANALYSI S -

  • GEOMETRI ES

GEOMETRI ES

Scaling 32%

Wedge 18% Block 50%

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SLIDE 13

PROBLEM PROBLEM

FOG FATALI TY ANALYSI S FOG FATALI TY ANALYSI S -

  • BOUNDARI ES

BOUNDARI ES Faults 6% Joints 63% Chromitite Layer 27% Dykes 4%

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SLIDE 14

PROBLEM PROBLEM

ROCK MASS CLASSI FI CATI ON SYSTEMS ROCK MASS CLASSI FI CATI ON SYSTEMS

1. 1.

Terzhagi Terzhagi’ ’s s

2. 2.

RQD RQD

3. 3.

Rock Structure Rating (RSR) Rock Structure Rating (RSR)

4. 4.

CSI R Geomechanics Classification CSI R Geomechanics Classification for jointed rock mass for jointed rock mass

5. 5.

Modifications to RMR for mining Modifications to RMR for mining

6. 6.

Stini Stini & & Lauffer Lauffer Classifications Classifications

7. 7.

Checklist methodology for hazard Checklist methodology for hazard identification in tunnels identification in tunnels

8. 8.

Rockwall Condition Factor (RCF) Rockwall Condition Factor (RCF)

9. 9.

Rock Tunneling Quality I ndex, Q Rock Tunneling Quality I ndex, Q

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SLIDE 15

PROBLEM PROBLEM

  • Simplicity as a measure of block size, inter block

Simplicity as a measure of block size, inter block shear strength, active stress & all critical factors shear strength, active stress & all critical factors associated with fog associated with fog’ ’s s

  • Easy to use underground

Easy to use underground

  • Simple relationship between support required,

Simple relationship between support required,

  • no support required and tunneling Q

no support required and tunneling Q-

  • index

index which can be easily modified to suit changing which can be easily modified to suit changing geotechnical conditions geotechnical conditions

Q Q -

  • SYSTEM APPLI CABI LI TY TO I MPALA

SYSTEM APPLI CABI LI TY TO I MPALA

Q Q

= = RQD RQD x x Ja Ja x x Jw Jw Jn Jr SRF Jn Jr SRF

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SLIDE 16

1.

  • 1. Introduction

Introduction 2.

  • 2. Locality Plan

Locality Plan

  • 3. Geological Setting
  • 3. Geological Setting
  • 4. Problem
  • 4. Problem

4.1 FOG Analysis 4.1 FOG Analysis 4.2 Rock Mass Classification Systems 4.2 Rock Mass Classification Systems 4.3 Q 4.3 Q-

  • System Applicability to Impala

System Applicability to Impala

  • 6. Conclusions
  • 6. Conclusions
  • 5. Case Studies
  • 5. Case Studies

5.1 Q 5.1 Q-

  • System Methodology

System Methodology 5.2 Q 5.2 Q-

  • I ndex Analysis for 10 Level Crosscut & 23 Level

I ndex Analysis for 10 Level Crosscut & 23 Level Conveyor Conveyor 5.3 Bolt Length Design for permanent mine openings 5.3 Bolt Length Design for permanent mine openings

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SLIDE 17

CASE STUDI ES CASE STUDI ES

Q Q – – INDEX METHODOLOGY INDEX METHODOLOGY :

:

  • Estimating Rock Quality Designation (RQD) From Scan line

Estimating Rock Quality Designation (RQD) From Scan line Measurements Measurements

Jd Jd = D + S + V = D + S + V RQD = 115 RQD = 115 – – 3.3 * 3.3 * Jd Jd

  • Jn, Jr, Ja, Jw & SRF Obtained As Described By Barton

Jn, Jr, Ja, Jw & SRF Obtained As Described By Barton

  • 10m Intervals

10m Intervals

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SLIDE 18

CASE STUDI ES CASE STUDI ES

Q Q – – INDEX ANALYSIS INDEX ANALYSIS :

:

  • No. 9
  • No. 9-
  • Shaft ~ 10 Level Crosscut

Shaft ~ 10 Level Crosscut

  • No. 14
  • No. 14-
  • Shaft ~ 23 Level Conveyor Decline

Shaft ~ 23 Level Conveyor Decline 89 Tunneling Quality Index Measurements : 89 Tunneling Quality Index Measurements :

  • 77 Along 10 Level Crosscut

77 Along 10 Level Crosscut

  • 12 Along 23 Level Conveyor

12 Along 23 Level Conveyor representing 890m of tunnel representing 890m of tunnel

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SLIDE 19

CASE STUDI ES CASE STUDI ES

10 20 30 40

E x tr e m e ly G o o d V e r y G o o d G o o d F a ir P o o r V e r y P o o r E x tr e m e ly P o o r E x c e p tio n a lly p o o r

Q - VALUE CATEGORIES Q U A N T IT Y

10 LEVEL CROSSCUT 23 LEVEL CONVEYOR

Distribution of Q Distribution of Q-

  • Index Values

Index Values

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SLIDE 20

CASE STUDI ES CASE STUDI ES

  • NO. 9
  • NO. 9-
  • SHAFT

SHAFT 10 LEVEL CROSSCUT 10 LEVEL CROSSCUT

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SLIDE 21

CASE STUDI ES CASE STUDI ES

  • NO. 9
  • NO. 9-
  • SHAFT

SHAFT 10 LEVEL CROSSCUT 10 LEVEL CROSSCUT

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SLIDE 22

CASE STUDI ES CASE STUDI ES

  • NO. 14
  • NO. 14-
  • SHAFT

SHAFT 23 LEVEL CONVEYOR DECLINE 23 LEVEL CONVEYOR DECLINE

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SLIDE 23

CASE STUDI ES CASE STUDI ES

  • NO. 14
  • NO. 14-
  • SHAFT

SHAFT 23 LEVEL CONVEYOR DECLINE 23 LEVEL CONVEYOR DECLINE

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SLIDE 24

CASE STUDI ES CASE STUDI ES

Rock Mass Quality, Q, vs Equivalent Dimension Rock Mass Quality, Q, vs Equivalent Dimension -

  • Plot

Plot

1 10 100

0.1 1 10 100 1000

Rock Mass Quality Q

E q u iv a le n t D im e n s io n

Unsupported - Barton Unsupported - Hartman 23 Level Conveyor 10 Level Crosscut

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SLIDE 25

CASE STUDI ES CASE STUDI ES

Rock Mass Quality, Q, vs Unsupported Span Rock Mass Quality, Q, vs Unsupported Span -

  • Plot

Plot

1 10 100 1000 0.1 1 10 100 1000 Rock Mass Quality Q

U n s u p p o r te d S p a n (m )

Unsupported

  • Barton

Unsupported

  • Hartman

10 Level Crosscut 23 Level Conveyor

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SLIDE 26

Barton Formulas Barton Formulas : :

CASE STUDI ES CASE STUDI ES

Equivalent Dimension = 2 * Q0.4 Unsupported Span = 2 * ESR * Q0.4 Hartman Modified Formulas Hartman Modified Formulas : : Equivalent Dimension = 1,56 * Q0.3442 Unsupported Span = 1,56 * ESR * Q0.3442

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SLIDE 27

CASE STUDI ES CASE STUDI ES

Bolt Length Design for Permanent Mine Openings Bolt Length Design for Permanent Mine Openings

Where, L - bolt length; B - excavation width; ESR (Excavation Support Ratio) - a value related to the intended use of the excavation and the degree of security, which is demanded of the system - For permanent mine openings the ESR = 1.6.

From Barton et al : L = 2 + 0.15*B ESR

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SLIDE 28

1.

  • 1. Introduction

Introduction 2.

  • 2. Locality Plan

Locality Plan

  • 3. Geological Setting
  • 3. Geological Setting
  • 4. Problem
  • 4. Problem

4.1 FOG Analysis 4.1 FOG Analysis 4.2 Rock Mass Classification Systems 4.2 Rock Mass Classification Systems 4.3 Q 4.3 Q-

  • System Applicability to Impala

System Applicability to Impala

  • 6. Conclusions
  • 6. Conclusions
  • 5. Case Studies
  • 5. Case Studies

5.1 Q 5.1 Q-

  • System Methodology

System Methodology 5.2 Q 5.2 Q-

  • Index Analysis for 10 Level Crosscut & 23 Level

Index Analysis for 10 Level Crosscut & 23 Level Conveyor Conveyor 5.3 Bolt Length Design for permanent mine openings 5.3 Bolt Length Design for permanent mine openings

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SLIDE 29

Conclusions Conclusions

FOG Analysis FOG Analysis : :

  • 95% of all falls of ground were 0,9m

95% of all falls of ground were 0,9m thick or less thick or less

  • nearly all falls of ground were related to

nearly all falls of ground were related to discontinuities in the rock mass discontinuities in the rock mass

  • large falls of ground are infrequent

large falls of ground are infrequent

  • conventional support would have been

conventional support would have been sufficient to prevent falls of ground sufficient to prevent falls of ground

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SLIDE 30

Conclusions ( Conclusions ( CONT.

CONT.)

)

Tunnel Quality I ndex Application Tunnel Quality I ndex Application : :

  • no rockmass classification systems are

no rockmass classification systems are general & require some modification in general & require some modification in a specific environment a specific environment

  • support to be introduced into tunnels

support to be introduced into tunnels with spans in excess of the modified with spans in excess of the modified prediction prediction

  • potentially large falls of ground should

potentially large falls of ground should be prevented by investigations & revealing be prevented by investigations & revealing un un-

  • favourable orientations of

favourable orientations of discontinuities discontinuities