Large diameter raise boring allows for faster excavation of non-horizontal mine access with less safety risks than traditional methods. Modern machines can excavate shafts over 1,000 meters long and 6 meters in diameter in a single pass. Key considerations for projects include stable ground conditions, adequate access and logistics planning, managing geotechnical risks, and selecting qualified contractors. Successful projects require thorough planning and mitigation of hazards to ensure safety and on-time completion.

1. L Di t R i B i i H d R kLarge Diameter Raise Boring in Hard Rock
An overview, its application and considerations
Author & Presenter: Patrick Hudd
Co‐author: Dennis Martin
Date: Tuesday 26th October, 2010
Location: Room C205 at 9am
MeMO 2010 – Large Diameter Raiseboring in Hard Rock: An overview, its application and considerations

2. C t tContents
I t d ti• Introduction
• Large diameter raiseboring, now and then
• Considerations for incorporating large
diameter raiseboring
• Project execution
• Summary and questions• Summary and questions

3. Raise Boring is
using machinery to effect a raise by drilling ausing machinery to effect a raise by drilling a
hole in either a one step or two step process.
d h l h d b h d bReamed holes had been achieved by engineers
such as Bade in 1949 but it was the development
of the Cannon‐Robbins raise drills in the late
1950s that gave us the forerunners of today’s1950s that gave us the forerunners of today s
raise drills.
HISTORY OF RAISE BORING

4. Th R i b i PThe Raiseboring Process
Pilot Ream Pilot Blindrill Ream ReamPilot
down
Ream
Up
Pilot
Up
Blindrill
Up
Ream
Up
Ream
Down

5. The Large Diameter RaiseboringThe Large Diameter Raiseboring
Process

6. Wh R i B i ?Why Raise Boring?
For most applications of non‐
horizontal development in rock raise
boring provides time and cost saving
benefits:
– Faster advance rates
– Less disturbance to the rock
structure
– Reduced labour costs
– Greater safety for operating
lpersonnel

7. L Di t N d ThLarge Diameter, Now and Then
• Traditionally in hard rock (>150• Traditionally in hard rock (>150
MPa) mining large diameter raise
boring was thought of as 3 to 4 m in
diameter and over 300 m in lengthdiameter and over 300 m in length
• Mine and ventilation engineers
were challenged to design systems
either incorporating such holes, or
slashing and modifying to suit
• Now single pass bored shafts of 6 m
in diameter and 1000 m in length
are being excavated

8. 0 C l d Si l d Sh f10 Largest Completed Single Pass Bored Shafts
Length Ground
Year Location m Dia. Machine Type MPa
1986 Deelkraal – RSA 1036 6.1 HG330 Norite 220
2010 Cadia Shaft – AUS 930 6.0 HG330 Volcanics 210
1988 Frank Shaft – RSA 1033 5.8 HG330 Norite 220
1997 Phalaborwa ‐ RSA 923 5.7 HG330 ? ?
1998 Amandulbult ‐ RSA 877 5.52 HG330 Norite 2201998 Amandulbult RSA 877 5.52 HG330 Norite 220
1999 Impala 11 – RSA 784 5.8 HG330 Norite 220
1998 Impala 1 – RSA 965 5.1 HG330 Norite 220
2008 Gwalia – AUS 800 5.52 HG330 Basalt 200
1993 Turffontein – RSA 1102 4.5 HG330 Norite 220
2007 Red Lake ‐ CAD 694 5.52 123R Basalt 180

9. Th t d T R i tThrust and Torque Requirements
• Consider a 1,000m long raise of 6 metre diameter through rock of 150 MPa UCS
• Thrust – required to overcome the dead weight of the drill string, plus the reamer and
cutter loading required to fracture the rock
• Weight of drill string over 1,000m @ 500kg per m 500tWeight of drill string over 1,000m @ 500kg per m 500t
• Weight of reamer and derrick 45t
• Cutter loading with 36# cutters @ 10t each 360t (3,530kN)
• Thrust required 905t
• Torque – rotational force to overcome the torsion in the drill string and components to
allow the cutters on the reamer to traverse the face and cut the rock
• Historical data and the Tamrock torque formula:• Historical data and the Tamrock torque formula:
– M = C x f x T x (D/2) x √P
• Torque required 509kNm

10. Currently Available Large DiameterCurrently Available Large Diameter
Machines
Machines
Thrust
(Tonne)
Torque
(kNm)
Rod Diameter
mm Available
Wirth HG380 1180 710 353 1Wirth HG380 1180 710 353 1
Wirth HG330 900 610 333 4
Atlas Copco 123RH 810 540 333 1
Atl C 123DC 810 540 333 1Atlas Copco 123DC 810 540 333 1
Strata 950RH 950 1000 333 and 356 5
Strata 850RH 850 1000 333 and 356 1
Redbore 100AC 1440 1000 368 1

11. Example Standard OperatingExample Standard Operating
Capability
6 5
5.5
6
6.5
4.5
5
ameter(m)
Robbins 97R
Robbins 123R
3
3.5
4
Raisedi
Strata 950
2
2.5
3
0 200 400 600 800 10000 200 400 600 800 1000
Length of raise (m)

12. Considerations for IncorporatingConsiderations for Incorporating
Large Diameter Raiseboring
• Blind Sink• Blind Sink
– When there is no access at the bottom
– When ground conditions are unstable
– When ground water is an issue– When ground water is an issue
– When the length and diameter rule out pilot and slash and raise boring
• Pilot and Slash (Pilot with Alimak or Raise Drill)
When there is access at the bottom– When there is access at the bottom
– When ground conditions are unstable
– When ground water is not an issue
– When finished diameter is greater than raise boring capabilitiesg g p
• Raise Boring
– When there is access at the bottom
– When ground conditions are stableWhen ground conditions are stable
– When ground water is not an issue

13. Four key questions that make large diameter raiseboring an option:

14. Information and technicalInformation and technical
considerations
•Geotechnical Information
–Ground conditions dictate what you can
and cannot do and planning for those
ground conditions is fundamental for a
successful project
Responsibility for the ground
conditions before, during and after
construction is with the Ownerconstruction is with the Owner.

15. G t h i l i k tGeotechnical risk assessment
Based upon McCracken & Stacey, Geotechnical risk assessment for large dimater raise‐bored shafts, 1989

16. A f d d dAccess – surface and underground
•Shift schedules, blast windowsShift schedules, blast windows
•Raise collars incl. location

17. Excavations required to enable theExcavations required to enable the
work

18. Excavations required to enable theExcavations required to enable the
work

19. Services and logisticsServices and logistics
•Electrical power
•Water
•Sumps
•Rods
•Waste handlingWaste handling

20. Safety, cost & schedule, riskSafety, cost & schedule, risk
•Safety
•Operator exposure to hazards is reduced, but not eliminatedp p ,
•Bottom horizon work
•Rod handling
•High voltage electrics high pressure hydraulics•High voltage electrics, high pressure hydraulics
•Cost & Schedule
•Early planning and scoping around four key questions
•Actual status and forecast of enabling works and machine availability
•Budget price and schedule, incl. why hole is required
•Risk and Mitigationg
•If risk is unacceptable, relocate, amend specification or method
•Probability of failure, end use of hole and service life

21. Project ExecutionProject Execution
•Procurement Strategy
•Client or contractor?
•Three main reasons to engage a contractor:
1 Can be done more expertly cheaply and quickly than with client1. Can be done more expertly , cheaply and quickly than with client
resources
2. Does not warrant the capital expenditure on equipment and
establishment of a team to carry out a one off job in aestablishment of a team to carry out a one‐off job in a
specialized field
3. May allow development to be undertaken concurrently with
existing operations for expansion or transitionexisting operations for expansion or transition
(after JAA James – Underground Mining Construction By Contract – Getting the Best For Principal and Contractor, 1985)

22. C t t S l tiContractor Selection
•Soundness of
reputation
•Competence of key
personnel
•Back‐up resources,
technical and
administrative
•Financial resources
•Current activities
•Safety track records•Safety track records
•Dependence on sub‐
contractors

23. T i l C i l F tTypical Commercial Format
NSW Guideline for Raiseboring Operations:NSW Guideline for Raiseboring Operations:
“A negotiated contract that is accurately scoped and includes systems that
h id tifi d d i k k d t ti l h d ith i t tihave identified and risk ranked potential hazards with appropriate actions
to control them. A contract which is fully scoped and completed prior to
project commencement, and is auditable throughout the contract term. A
contract which minimises the likelihood of surprises which may adverselycontract which minimises the likelihood of surprises which may adversely
affect the safety performance of either party.”

24. O ti C id tiOperating Considerations
• Replacement equipment availability in case of catastrophic failure• Replacement equipment availability in case of catastrophic failure
– Damage or loss of drill string
• Mobilization setup and demobilization require detailed planning• Mobilization, setup and demobilization require detailed planning
– A clear definition of Client and Contractor responsibilities
• Ideally long, large diameter bored shafts are verticalIdeally long, large diameter bored shafts are vertical
– If a vertical shaft is critical then special tooling is need for drilling the pilot hole
• Removal of the cuttings to avoid interruptions during the reaming cycle is g p g g y
extremely important and tends to be where delays and operating issues
arise
– Capital required to successfully bore a 1000 m long, 6 m shaft is >$12 million USD
– With a crew of six the delay cost is >$500 USD/h

25. Summary
Questions?Questions?