CRITERIA FOR SELECTION OF ADVANCED

TECHNOLOGY OF TUNNELING IN
HARD ROCK MINING AND A CASE STUDY.

By:- NIRMAL KUMAR MUNDA

114MN0280

INTRODUCTION
Atunnelis an underground or underwater passageway, dug through the surrounding
soil/earth/rock and enclosed except for entrance and exit, commonly at each end.
A tunnel may be for foot or vehicular roadtraffic, forrail traffic, or for acanal.
The Delaware Aqueduct in New York, USA is the longest tunnel of any type in the
world at 137 km (85 mi).
Factors for all types of tunnel progressing:
Excavate
Dispose of the muck
Line the excavated ground.

Mine tunnels:

TYPES OF TUNNELS

used during ore extraction, enabling labourers or

equipment to access mineral and metal deposits
deep inside theearth.
These tunnels are made using similar techniques as
other types of tunnels, but they cost less to build.
Mine tunnels are not as safe as tunnels designed
for permanent occupation, however.

Photo courtesy National Photo Company C

Public works tunnels

carry water, sewage or gas lines across great distances.
The earliest tunnels were used to transport water to, and sewage away from, heavily
populated regions.
By A.D. 97, nine aqueducts carried approximately 85 million gallons of water a day
from mountain springs to the city of Rome.
Transportation tunnels or canals
tunnels to pass efficiently through an obstacle, such as
a mountain .
The Holland Tunnel, completed in 1927, was one of the
Photo courtesyKmf164/Creation Commons Attribution Share-alike License
first roadway tunnels and is still one of the world's greatest
Traveling through the Holland Tunnel from Manhattan to New Jersey

engineering projects

FACTORS AFFECTING EXCAVATION OF

ROCKS
Mineralogical composition of rock
Texture and fabric
Petrographic features
Structure
Rock mass
Strike and dip of beds in relation to face of excavation
Intensity of tectonic disturbances
Degree of weathering

TUNNELING METHODS IN HARD ROCK

MINING
Pipe jacking/shield machines
Road headers
Hammer tunneling splitters
TBMs
Drill and blast
Cut and cover

The selection of a tunnelling method depends on many factors, including:

Desired rate advance
Area of tunnel cross section
Available capital investment
Contractors and suppliers availability
Intact rock properties
Rock mass properties
Desired cutting geometry
Operational parameters
Machine specification
Tunnel dimensions
Tunnel geometry
Length of tunnel,
total volume to be excavated
Geological and rock mechanical conditions
Ground water level and expected water inflow
Vibration restrictions
Allowed ground settlements

PIPE JACKING
Pipe jacking is a technique of installing pipes underground using small diameter
TBMs.
Usually termed as micro tunnelling, this method is best deployed in cohesive soils.
This method can now be employed either in cohesive or non cohesive soils, in dry
or watery conditions, to jacking through very hard rock and ground conditions
comprised of mixed composites, such as cobbles and big boulders.

ROAD HEADERS

A roadheader is an entry-boring machine, which bores the entire section of the

entry in one operation.
A roadheader is basically categorized primarily on types of cutting heads, traverse
or longitudinal, and on the basis of types of loading assembly- gathering arms,
spinner loaders, scraper conveyor loaders, two lateral loading beams, or one
central loading beam.

:
A longitudinal roadheader by Mitsui Miike Machinery Co., Ltd.

(Source: Rock ExcavationHandbook, Chapter 6:Tunnelling)

INDIATIVE DIAGRAM FOR ROADHEADER SELECTION

HTTPS://MININGANDBLASTING.FILES.WORDPRESS.COM/2009/09/ROCK-EXCAVATION-HANDBOOK-TUNNELING.PDF

HAMMER TUNNELING SPLITTERS

Impact hammers have been used in mining industries since 1960s.
over-sized boulders, heavily reinforced concrete structures or steel slag is applied.
works on two mechanisms of breaking penetrative breaking and impact breaking.
Penetrative breaking relates to softer materials that are demolished by combination
of stress waves and wedge effect.
Hydraulic impact hammers have been applied tunnelling in Istanbul with almost
11kms of tunnels have been excavated since 1992. Here, impact hammers have
been applied to tunnels of 36 m2 cross section and in rock with RQD ranging from 0
to 100.
Hammer tunneling is successful compared to drilling and blasting when the
fractured rock structure makes controlled blasting hard to achieve.

CUT AND COVER

Cut and cover tunneling is well proven technique for shallow tunnels.
Top-down Method

In the cut-and-cover top-downor diaphragm wall method, the opposite process takes place in
constructing the tunnel.
Atrencheror trench cutter is typically used to dig a trench out of the the ground first before concrete
walls are built.
This processes consists of using a slurry mixture to build aslurry wall.
The slurry wall provides temporary support to the sides of the trench before concrete is poured for a
permanent wall structure.
Once the concrete walls of the tunnel are completed, the roof of the tunnel is constructed and the
surface roadway restored.
Excavationof the tunnel is then carried out through openings in the tunnel roof top-down to the
tunnel floor.
The tunnel floor slab is the last part of construction to be completed.

DRILL AND BLAST

This is the most conventional method of tunnelling and is still practiced and
favoured for shorter tunnels, in hard rocks, and where time is not constraint.
Modern drill and blast excavation has basic approach of:
to drill a pattern of small holes
load them with explosives
the detonate those explosives
hence creating an opening in the rock
Procedure:
1)Drilling
holes are drilled by using pneumatically operated rock drills.
size of drill bits used should be such that diameter of the hole is 6mm larger than
diameter of hole
2)Blasting

DRILL AND BLAST CYCLE

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TBM(TUNNELLING BORING MACHINE)

Because of its capabilities to attain high rates of advance in civil tunnel
construction, the tunnel boring machine is gaining popularity and interest towards
its applications in underground mine development.
TBMs have been used for the construction of tunnels for access,conveyance,
drainage, exploration, and water diversion purposes for new and existing mines.

COMPARISON OF ALL METHODS

Tunneling Methods

Advance Rate (m/day)

Cross-section Area (m2) /

Dia (m)

Rock Properties

Comments
Primarily for laying pipelines;
small cross-section and limited
capability in hard rocks show
little scope of its use in
underground mining

Pipe Jacking

5 20

12 mm (0.5") 3.6 m (12')

Best suited for cohesive soil;

can also be applied to noncohesive and dry conditions
and in hard rocks.

Hammer Tunneling

2 10

Up to 30 m

Breaking, mucking and

Low to medium strength; RQD:
reinforcement can go together;
0 100
low investment

Low investment, 15% - 30% of

TM investment for same crosssection; can be rented; can be
delivered and ready for
operation in 3-6 months; free
space and accessibility; can
handle a variety of subsections

Up to 140 MPa (UCS); can

adapt to changing rock mass
conditions

Roadheaders

5 15

Up to 45 m

TBMs

15 - 50

Up to 160 m

From 20 to 140 MPa (UCS); can Fabrication period of around 12

be frabricated to a variety of
months; Onsite set up time 3-6
ground conditions
months

Drill & Blast

3.5 m - 5 m & 7 - 15 m
(without rock support
installation)

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RANGE OF METHODS COMPARED TO UNIAXAL COMPRESSIVE STRENGTH AND TUNNELING
METHODS IN DIFFERENT ROCK/SOIL CONDITIONS

TBM
From the above considerations and facts, TBMs are the most suitable technical
considerations for the constructions of tunnels in mining projects.
The greatest use of TBMs for mining has been for mine access at the Stillwater
Mine in USA, where a third campaign of TBM excavation is currently underway.
In the early 1990, a TBM was used for the development of more than 12 km of
tunnels at the San Manuel Mine in Arizona. A 4.6 diameter open main beam type of
TBM was used.

New TBM for Stillwater Mine

1993 TBM at the San Manuel Mine

Table 1 TBM use at mining projects.

Project

Location

Yeara

Length, km

Size, m

Step Rock Iron

Canada

1957

0.30

2.74

Nchanga

Zambia

1970

3.2

3.65

USA

1977

0.20

7.4

South Africa

1977

0.30

1.84

Oak Grove
Blyvoor
Fosdalen

Norway

1977

670

3.15

Blumenthal

Germany

1979

10.6

6.5

Westfalen

Germany

1979

12.7

6.1

Canada

1984

3.6

7.6

Autlan

Mexico

1985

1.8

3.6

Kiena

Canada

1986

1.4

2.3

Stillwater EB

USA

1988-91

6.4

Fraser (CUB)

Canada

1989

1.5

2.1

Rio Blanco

Chile

1992

11.0

5.7

San Manuel

USA

1993

10.5

4.6

Cigar Lake

Canada

1997

> 20

4.5

Port Hedland

Australia

1998

1.3

5.0

Stillwater EB

USA

1998-01

11.2

4.6

Mineral Creek

USA

2001

4.0

6.0

South Africa

2001

0.35

2.4

Italy

2003

8.5

4.9

Donkin Morien

Amplats
Monte Giglio
Tashan Coal

China

2007

4.9

Ok Tedi

PNG

2008

4.8

5.6

Los Bronces

Chile

2009

8.0

4.2

Stillwater Blitz

USA

2012-13

6.8

5.5

Grosvenor Coal

Australia

2013

1.0

8.0

Oz Minerals

Australia

2013

11.0

Northparkes

Australia

2013

2.0

5.0

Chile

2014

6.0

10.0

El Teniente
a

Year of start of project.

Planned TBM excavation.

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5.8

KEY TECHNICAL CONSIDERATIONS

Geological conditions:

TBMs are most appropriate applied in homogeneous rock conditions that are conductive for
excavation, including very strong rock varying from 150 MPa to 250 MPa.
Extremely strong, massive(widely jointed) and abrasive rock will impact TBM progress; however,
larger(19 in. Or 483mm) cutters in conjunction with high power capacity can result in attractive
TBM progress rates.
Depth of cover/potential overstressing:
Evaluation of the potential for overstressing requires knowledge of the uniaxial compressive
strength (UCS) and in situ stresses.
TBMs are not much appropriate for long, deep tunnels, where the lengths may be subjected to
low rock strengths. Here drill and blast tunnels works with high capacity tunnel support.
Site access and terrain:
Appropriate site access and terrain with low gradient rocks must be considered for mobilization of
TBM equipment.
The weight of large size TBMs(>8-10 m) can exceed 130 te, so special lowboy vehicles are
typically required to bring TBMs.
While many mine sites are well established with haul roads, declines, shafts TBMs can be
accessed to the mine through this paths.

 TBM launching requirements:

The site laydown for a TBM is much larger than that for a drill and blast operation,
and therefore a great risk of rockfall/avalanches impact TBM operations during
constructions.
Cutter geometry:
Cutting tools provide for the transmission of energy generated by the machine to the
rock in order to cause fragmentation.
Single disc cutters are the most commonly used roller cutters for hard rock.
They are the most efficient types of rolling cutters since the entire capacity of the
bearing is concentrated into a single, narrow edge.

Single disc cutters. Source: https://miningandblasting.files.wordpress.com

http://inside.mines.edu/

 Contractor experience:
it includes key skilled labour positions, such as TBM
operators, mechanics and electrician, who are
professionally trained in handling and operating TBMs.
Concrete linings for TBM tunnel:
In some cases it may be cost effective to design tunnel
lining with concrete in order to minimize maintenance
requirements over the life of a mine.
Precast concrete segmental linings are commonly used
for the major urban metro and water/waste wear
projects /, as well as for hydropower tunnels in mixed
bedrock conditions.

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Spoil disposal and handling:

Spoil can be removed by rail wagons or conveyors.
Conveyor systems are generally used in long tunnels for faster and removal of large
volume of material.
Spoil from TBM tunnels may be used as backfill for the tunnel invert to construct a
flat bottomed roadway, as commonly required for many tunnel uses.
Logistics:
The main logistics to consider for the use of TBMs at mine sites is the availability of
power.
Power requirements for TBMs vary with size and can range from 1.5 MW for a 4-mdiameter TBM up to 8MW for a 10-m diameter TBM.
Additional power requirements for TBM tunnel constructions include ventilation
and lighting.

LATEST MODEL OF
TBM
Herrenknecht tunneling boring machines Canigou and Alberas are compact
powerhouse:equipped with an installed power of 1250kW, they have a torque of
2000 kNm with a cutterhead diameter of 4.3 meters. The tunnel boring machines
have a lenghth of 301 and 253 meters respectively and weighs 620 tonnes. The
double shield TBMs started at their launch portals in March and October 2012 to
excavate and line 8.2 km long tunnel through the hard rock of the Catalan Pyreness.

"Canigou" (M-1619M) - one of the two Herrenknecht Double Shield TBMs ( 4,256mm) for the excavation of the INELFE Tunnel project.

The back-up systems of the two Double Shield TBMs are designed for high tunnelling performances, allowing the storage of the segments and other material for two
ring building
sequences.

CASE
STUDY
San Manuel Mine Tunnel
Robbins TBM extends the life of a large underground mine
Machine Type

Main Beam TBM

Diameter

4.6 m (15.1 ft)

Tunnel Type

Mining

Tunnel Length

10.5 km (6.5 mi)

Owner

Magma Copper Company

Contractor

Frontier-Kemper Constructors Inc / Deilmann-Haniel GmbH

Joint Venture

Location

San Manuel, Arizona, USA

 The project owner, Magma Copper Company, awarded the construction contract to a joint
venture of Frontier-Kemper Constructors Inc. and Deilmann-Haniel GmbH. The joint venture
chose a 4.6 m (15.1 ft) Main Beam Robbins TBM to bore the mining tunnel.
Geology
The Lower Kalamazoo geology is quite complex, consisting of orebodies, porphyry, and
granodiorite. The tunnel route includes numerous faults and dikes it passed through the
San Manuel fault six times and the Virgin Fault five times. Much of the rock had been
weakened by hydrothermal metamorphosis.
TBM
Robbins designed the new hard rock Main Beam TBM specifically for the geological
conditions. The 4.6 m (15.1 ft) diameter cutterhead could reverse rotational direction to
prevent jamming when it encountered fractured rock. The machine also featured thirty-three
17 inch (432 mm) backloading disc cutters for greater safety.
Boring began on November 11, 1993 in a specially prepared concrete chamber. There were
no major problems crossing the San Manuel Fault, but wet clay at the Virgin Fault resulted in
slow boring. The TBM continued to encounter soft clay and crumbling ground.
Robbins and the contractors added several features to the machine to optimize performance.
They increased muck flow through the cutterhead, increased cutterhead torque, and added
additional rock support to the tunnel. After the initial modifications, TBM performance greatly
improved. Daily advances tripled to 22.94 m (75.3 ft) per day for the first 15 months of
boring and the machine averaged more than 30 m (98.5 ft) per day for the rest of the project.
The TBM stayed on schedule and holed through on December 4, 1995.

CONCLUSION
Tunneling is one of the most hazardous projects in engineering and construction. It is
also one of the most expensive. For this reason, extensive planning and surveying
goes into the pre-excavation stage of the project.
The applicability of TBMs for mining projects offer benefits where timing of essence
in order to advance mining development and achieve early startup operations. TBMs
are not much suitable in some cases of weak rock strata and long tunnel projects as
compared to drill and blast system. So TBMs should be modified for some of the
issues such as the multiple speed cutterheads to provide more torque at lower speed
for operating highly fractured ground.

1.

REFERENCE
S
https://en.wikipedia.org/wiki/Tunnel

2. https://en.wikipedia.org/wiki/Drilling_and_blasting
3. http://science.howstuffworks.com/engineering/structural/tunnel1.htm
4. http://www.magmineserv.com/cave.html
5. http://jme.shahroodut.ac.ir/pdf_4_72b0cc9fcdcecffc8e4b8fff3c75aa59.html
6. http://www.umich.edu/~gs265/tunnel.html
7. www.slideshare.net
8. www.nodig-construction.com

THANK YOU