L Di t R i B i i H d R kLarge Diameter Raise Boring in Hard RockAn 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

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

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

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

The Large Diameter RaiseboringThe Large Diameter RaiseboringProcess

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

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

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

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

Currently Available Large Diameter Currently Available Large Diameter Machines

MachinesThrust (Tonne)

Torque (kNm)

Rod Diameter mm Available

Wirth HG380 1180 710 353 1Wirth HG380 1180 710 353 1Wirth HG330 900 610 333 4Atlas Copco 123RH 810 540 333 1Atl C 123DC 810 540 333 1Atlas Copco 123DC 810 540 333 1Strata 950RH 950 1000 333 and 356 5Strata 850RH 850 1000 333 and 356 1Redbore 100AC 1440 1000 368 1

Example Standard Operating Example Standard Operating Capability

6 5

5.5

6

6.5

4.5

5

amet

er (m

)

Robbins 97R

Robbins 123R

3

3.5

4

Rai

se d

i Strata 950

2

2.5

3

0 200 400 600 800 10000 200 400 600 800 1000Length of raise (m)

Considerations for Incorporating Considerations 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

Four key questions that make large diameter raiseboring an option:

Information and technical Information 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.

G t h i l i k t Geotechnical risk assessment

Based upon McCracken & Stacey, Geotechnical risk assessment for large dimater raise‐bored shafts, 1989

A f d d dAccess – surface and underground

•Shift schedules, blast windowsShift schedules, blast windows

•Raise collars incl. location

Excavations required to enable the Excavations required to enable the work

Excavations required to enable the Excavations required to enable the work

Services and logisticsServices and logistics•Electrical power

•Water

•Sumps

•Rods

•Waste handlingWaste handling

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

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)

C t t S l tiContractor Selection

•Soundness of reputation•Competence of key personnel•Back‐up resources, technical andadministrative•Financial resources•Current activities•Safety track records•Safety track records•Dependence on sub‐contractors

T i l C i l F tTypical Commercial FormatNSW Guideline for Raiseboring Operations:NSW Guideline for Raiseboring Operations:

“A negotiated contract that is accurately scoped and includes systems thath 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 actionsto control them. A contract which is fully scoped and completed prior toproject commencement, and is auditable throughout the contract term. Acontract which minimises the likelihood of surprises which may adverselycontract which minimises the likelihood of surprises which may adverselyaffect the safety performance of either party.”

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 yextremely 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

Summary

Questions?Questions?