A Review of Application and Benefits of

Thin Spray-On Liners for Underground

Rock Support in South African Mines

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

8th South African Young Geotechnical

Engineers’ ConferenceCultivating the Future of Geotechnics

2

Introduction

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Budget

Planned return on

investment

Safety

Business aim of mining

operations

(Stacey, 2001; 2009)

3

Introduction - continued

Potvin et al., 2001

• 90% of rockfall injuries involve rocks smaller than one metric tonne.

Lacerda, 2004

• In USA metal mines in 1996, small rocks weighing 11-kg or less were responsible for 65% of all reported injuries and fatalities.

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Mining roof topElectricity

2%

Machinery

4%

S/W

Installation

5%

Rallbound

Equipment

10%

Trackless

Mobile

Machinery

16%

General

18%

Fall of

Ground

35%

Other

7%

Explosives

3%

(Web

ber

-Yo

ung

man

& V

an W

yk

, 2

00

9)

4

Introduction - continued

http://miningandconstruction.com/construct

ion/behind-the-gray-walls-the-art-of-

shotcreting-2485/

http://www.tensarcorp.com/Applicati

ons/Mining/mining-roof-and-wall-

support#

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

5

TSLs - Definition

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

(Ferreira, 2012) (Sudbury Mining Solutions Journal, July 2012)

6

TSLs – History and Background

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

7

TSLs – Composition, Properties & Type

Reactive or Non-reactive

Polymer based

Water basedPolyurethane/

Polyurea

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Polymer base and Mixture type

8

Support Mechanism/Analysis of TSLs

Adhesion Tensiona)

Extent of de-

bonding

Adhesion

failureb)

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Shear failure

fracture

zone

depth

fabric forces

tendon forces

tendon spacing

contributory areacontributory area

(Kuij

per

s et

al.

, 2004)

9

Application of TSLs in Mines

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

DescriptionRock Mass Rating

(%)

TSL Thickness

(mm)Bolting pattern1

Development drift (walls)45 - 65

2 - 31.8 m x 1.5 m2

>65 1.8 m x 1.5 m3

Development drift (roof or

back)

45 - 653 - 4

1.8 m x 1.1 m4

>65 1.8 m x 1.3 m4

Production headings (lower

wall)

45 - 65

2 - 3

1.8 m x 1.5 m5

>65 Boltless or spot bolting5

Production headings (roof

and back)

45 - 653 - 4 1.8 m or 2.4 m x 1.1 m4

>65

Note:1Mechanical bolts.

2Bolting after every two rounds of advance.3Indefinitely delayed with bi-annual audits.

4Install before or immediately after liner.5Installation can be delayed.

Tentative application guidelines for TSLs

(Esp

ley

etal

,1999)

10

Benefits from use of TSLs in SA Mines

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Reduction in Fatalities

Increased Productivity

Effective Cover against Weathering

Flexible and

Elastic

Rapid Curing Times

Reduced Material Handling

11

Benefits – Product Comparisons (cost, application and time)

(Fer

reir

a, 2

012)

Description Shotcrete

(± 25mm)

KT 2C

(± 5mm) 3m2

KT White

(± 5mm) 3m2

KT Grey

(± 5mm) 3m2

KT Fast

(± 5mm) 3m2

Approximate ex

factory product

cost per m2

R85 R95 R85 R65 R85

Approximate

dedicated labour

cost per m2

R125 R55 R55 R55 R55

*Approximate

Total cost per m2 R210 R150 R140 R120 R140

ReboundPoor (lots of

material)Hardly any Hardly any Hardly any Hardly any

Bags per m2

Kg per m2

3.5

88

0.33

8.35

0.33

8.35

0.33

8.35

0.33

8.35

Ease of Application Cumbersome Easy Easy Easy Easy**Time to cover 45

m2 (conventional

application)

150 Minutes 55 Minutes 55 Minutes 55 Minutes 55 Minutes

Equipment Large Small Small Small Small

Interference with

development cycleHigh Minimal Minimal Minimal Minimal

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

12

Benefits – Early Age Properties Comparison

(Lac

erda,

2004)

Elapsed TimeNon-Reactive TSL Fiber Reinforced Shotcrete

MPa PSI MPa PSI

Bond Strength

1 : 15 hr : min 0.30 44

2 : 30 hr : min 0.40 58

3 : 45 hr : min 0.50 73

5 : 00 hr : min 0.55 80

6 : 00 hr : min 0.60 87

8 : 00 hr : min 0.2 29

12 : 00 hr : min 0.3 42

24 : 00 hr : min 0.5 71

25 : 00 hr : min 1.20 174

40 : 00 hr : min 1.50 218

7 days 2.00 290

28 days 1.7 239

Tensile Strength

5 hours 1.5 218

8 hours 1.0 145

24 hours 2.0 290 1.7 247

7 days 2.2 312

28 days 2.3 328

6 weeks 4.0 580

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

13

Benefits – Reduction in Fatalities

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Relation between injuries and TSLs usage in South African

Mines (1998 – 2002)

0

200

400

600

0 20 40 60 80 100

Inju

ries

(T

ota

l co

un

ts)

TSL usage (Percentage)

(Adam

s, 2

002)

14

Conclusion

Five attributes of Innovation

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

UptakeRelative

Advantage

Compatibility

Complexity

Trialibility

Observability

(Rogers, 2003)

15

Conclusion

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za

Knowledge

Persuasion

Decision

Implementation

Confirmation

Five stages of innovation process

(Rogers, 2003)

THANKS

16

Jjuuko Samuel

Department of Civil Engineering

University of Cape Town

smljju001@myuct.ac.za