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The impact of tunnels diameters to the performance of TBM in hard rock

1. The impact of tunnel
diameter on the performance
of TBMs in hard rock
J. Hassanpour
•School of Geology, College of Science,
University of Tehran
•Member of board of directors of Iranian
tunneling association (IRTA)

2. At present, TBM diameter is generally between 3 and 15 m. The larger the
TBM diameter, the greater technical difficulty in TBM design,
manufacture, transportation, assembly and construction, while the smaller
TBM diameter results in narrow working space and the difficulty in
equipment layout.
The impact of tunnel diameter on the performance of TBMs in hard rock
The tunnel diameter can significantly impact the performance of a tunnel
boring machine (TBM) in various ways. Here are some key points to
consider:
•Ground Conditions: The diameter of the tunnel can influence the stability of
the ground surrounding the excavation. Larger tunnels may require more ground
support measures, which can affect the overall project timeline and budget.
•Handling of spoil: the size of the tunnel diameter will also impact the method
of spoil removal. Smaller tunnels may allow for easier handling and
transportation of spoil, while larger tunnels may require more complex spoil
removal systems.
•Operating parameters: Rotation speed of cutterhead, Number of cutters, etc.
•Machine performance
•….
Introduction

3. On September 10, 2021, the
world’s largest diameter hard
rock TBM “Caucasus” started to
bore a 9km tunnel in Georgia
and on April 23, 2024, broke
through, completing its
construction assignment 30 days
early.
Kvesheti-Kobi highway
tunnel project
With a maximum overburden of 1121m, the TBM completed 8860m of boring with no
intermediate access, reaching the maximum daily advance rate of 20m and the
maximum monthly advance rate of 426m. The geology is mainly tuff and marl, with a
maximum rock strength of 130MPa.
The impact of tunnel diameter on the performance of TBMs in hard rock
Caucasus TBM
Introduction

4. The machine is, according to CREG, the largest
diameter single shield hard rock TBM in the world to
date.
The impact of tunnel diameter on the performance of TBMs in hard rock
Caucasus TBM
Kvesheti-Kobi highway
tunnel project
Introduction

5. The machine is, according to CREG, the
largest diameter single shield hard rock
TBM in the world to date.
The impact of tunnel diameter on the performance of TBMs in hard rock
Caucasus TBM
Kvesheti-Kobi highway
tunnel project
Introduction

6. The impact of tunnel diameter on the performance of TBMs in hard rock
Kvesheti-Kobi highway
tunnel project
Introduction

7. Nowsood water
conveyance tunnel
project, Lot 2, 6.73m
Nowsood water
conveyance tunnel
project, Lot 1A, 5.5m Karaj water
conveyance tunnel
project, 4.65m
Kvesheti-Kobi highway
tunnel project, 15.08m
The impact of tunnel diameter on the performance of TBMs in hard rock
Introduction

8. Nowsood water
conveyance tunnel
project, Lot 2, 6.73mNowsood water
conveyance tunnel
project, Lot 1A, 5.5m
Karaj water
conveyance tunnel
project, 4.65m
Kvesheti-Kobi highway
tunnel project, 15.08m
The impact of tunnel diameter on the performance of TBMs in hard rock
Introduction

9. Diameter = 15.08 m
Weight = 3900 ton
Maximum thrust = 22600ton
Power = 9900 kW
Cuterhead rotation speed = 0-3rpm
Number of cutters = 98
Cutters spacing = 80 mm
Diameter = 6.73 m
Weight = 90 ton
Maximum thrust = 2500 ton
Number of thrust cylinders = 10
Thrust stroke = 0.8 m
Power = 350 kW
Cutterhead torque = 2967 kN.m (Normal)
Cuterhead rotation speed = 0-9 rpm
Number of drive motors = 6
Number of cutters = 42
Cutters spacing = 90 mm
Cutter diameter = 17 inch
The impact of tunnel diameter on the performance of TBMs in hard rock
Introduction

10. Unprecedented in-tunnel
diameter conversion of
the largest hard rock
TBM in the United States
The impact of tunnel diameter on the performance of TBMs in hard rock
The Robbins TBM is
understood to be the
world’s largest variable
diameter TBM and
completed an 11.5m
diameter drive for the first
2.7km of the Mill Creek
Drainage Relief Channel
tunnel before converting to
drive another 5.1km with a
9.9m diameter.
Introduction

11. The impact of tunnel diameter on the performance of TBMs in hard rock
Unprecedented in-
tunnel diameter
conversion of the
largest hard rock
TBM in the United
States
Introduction

12. The impact of tunnel diameter on the performance of TBMs in hard rock
With an excavation
diameter of 11.09
meters and a total
length of 137
meters, the TBM is
the first large-
diameter hard rock
tunneling machine
China has exported.
It will be used for
one of the world’s
largest cross-section
water diversion
project in Australia,
the Snowy 2.0.
Introduction

13. The impact of tunnel diameter on the performance of TBMs in hard rock
With an excavation diameter of 11.09 meters and a total length of 137 meters, the TBM
is the first large-diameter hard rock tunneling machine China has exported. It will be
used for one of the world’s largest cross-region water diversion project in Australia, the
Snowy 2.0.
Introduction

14. The impact of tunnel diameter on the performance of TBMs in hard rock
Introduction
The 14.38m diameter rock
Robbins TBM used for the
Niagara Tunnel project was
the largest rock TBM in the
world.

15. The impact of tunnel diameter on the performance of TBMs in hard rock
In order to generate a general guidance on determination of some of TBM
specifications, a database including 262 TBMs’ design parameters is
established. The statistical relationships between the design parameters of
262 TBMs (72 open, 24 single shield, 41 double shield, 86 EPB and 39
slurry TBMs) manufactured after 1985 in the world are investigated and
theoretical concepts behind the relationships between TBM diameter and
installed thrust capacity, nominal cutterhead torque capacity, total weight,
maximum rotational speed of cutterhead, and number of disc cutters are
discussed.
Ates et al. (2014)
Comparison of operating and cutting tools
design parameters

16. The relationship between
number of tools and TBM
diameter
The impact of tunnel diameter on the performance of TBMs in hard rock
Changes in operating and cutting tools
design parameters
Number of disc cutter

17. The impact of tunnel diameter on the performance of TBMs in hard rock
Cutter load
Cutter force Fc of the discs as a function of
the diameter (Wittke et al., 2007)
The cutter load F
n of the discs depend on the disc diameter
and on the geotechnical conditions (e. g. the unconfined
compressive strength of the intact rock) and range from
100 to 300kN
Comparison of operating and cutting tools
design parameters

18. To control vibrations, the linear
velocity of the cutter, v, is limited to
approx. 150 m/min. Another reason to
limit the rotation speed (i.e. RPM) is
to avoid overly large centrifugal forces
of the rock chips. Therefore, for given
R
max values, RPM is also limited.
The impact of tunnel diameter on the performance of TBMs in hard rock
Comparison of operating and cutting tools
design parameters
Rotation speed of disc cutters

19. The impact of tunnel diameter on the performance of TBMs in hard rock
The relationship between
cutter rolling distance and
TBM diameter
Comparison of operating and cutting tools
design parameters
Cutter rolling distance

20. Geology: Folded and faulted sedimentary and
pyroclastic rocks + Intrusive rocks
Eng. Geol.
Unit
Lithology UCS
(MPa)
RQD
(%)
R1 Limestone 60 60
R2 Tuff 100 80
R3 Granodiorite 150 95
R3-1 Sandstone 150 95
R4 Faulted rocks<50 <25
Tunnel length: 8914m
The impact of tunnel diameter on the performance of TBMs in hard rock
Comparison of the required number
of disc cutters
Machine type: Single shield

21. The impact of tunnel diameter on the performance of TBMs in hard rock
Estimating number of required disc cutters in
1000m of different rock types
Input parameters: CAI, CLI, VHNR, UCS
Comparison of the required number
of disc cutters

22. Eng. Geol.
Unit
Lithology UCS
(MPa)
VHNR H
f
(m
3
/cutter)
Number of
req. cutters
R1 Limestone 60 400 1600 30
R2 Tuff 100 700 700 69
R3 Granodiorite 130 800 350 208
R3-1 Sandstone 130 850 350
R4 (FZ) Faulted rocks<50 500-7002200 3
Sum 310
The impact of tunnel diameter on the performance of TBMs in hard rock
R
3; R
3-1
R
2
R
1
R
4
D
TBM=5m
Estimation of disc cutter life based on rock
properties
Comparison of the required number
of disc cutters
Disc cutter life prediction chart (UT model)
(Hassanpour et al. 2015)

23. Eng. Geol.
Unit
Lithology UCS
(MPa)
VHNR H
f
(m
3
/cutter)
Number of
req. cutters
R1 Limestone 60 400 1600 270
R2 Tuff 100 700 700 624
R3 Granodiorite 130 800 350 1873
R3-1 Sandstone 130 850 350
R4 (FZ) Faulted rocks<50 500-7002200 24
Sum 2791
The impact of tunnel diameter on the performance of TBMs in hard rock
Estimation of disc cutter life based on rock
properties
R
3; R
3-1
R
2
R
1
R
4
D
TBM=15m
Comparison of the required number
of disc cutters
Disc cutter life prediction chart (UT model)
(Hassanpour et al. 2015)

24. Eng. Geol.
Unit
Lithology UCS
(MPa)
RQD
(%)
FPI
(kN/c/mm/rev)
R1 Limestone 60 60 15
R2 Tuff 100 80 32
R3 Granodiorite 150 95 60
R3-1 Sandstone 150 95 60
R4 Faulted rocks <50 <25 10
The impact of tunnel diameter on the performance of TBMs in hard rock
R3
R2
R1
R4
Comparison of the construction
schedule of the tunnel
Rock mass breability prediction chart (UT model)
(Hassanpour et al. 2015)

25. The impact of tunnel diameter on the performance of TBMs in hard rock
D
TBM=5m
Comparison of the construction
schedule of the tunnel

26. The impact of tunnel diameter on the performance of TBMs in hard rock
1) Normal tunneling activities
times
2) Delay times due to adverse
geological conditions
3) Unforeseen delays caused by
project mismanagement.
•Boring
•Muck transportation
•Cutters Inspection
•Cutter Change
•Re-gripping
•Ring building
•Machine repairment
•Back-up repairment
•Others
•High water pressure zones
•Unstable ground in fault and
crushed zones
•High-stress zones in deep
tunnels
•Very hard and abrasive
grounds
•Others
•Lack of precast segments
•Power outage
•Lack of construction
materials (cement, ...)
•Inexperienced operators and
unskilled workers
•Others
Comparison of the construction
schedule of the tunnel

27. The impact of tunnel diameter on the performance of TBMs in hard rock
Comparison of the construction
schedule of the tunnel
Performance parameters estimated for a 5m diameter single
shield machine to complete a 9-kilometer tunnel
518 Days

28. The impact of tunnel diameter on the performance of TBMs in hard rock
D
TBM=5m
Comparison of the construction
schedule of the tunnel
Construction schedule and tunnel activities estimated for a 5m diameter single shield machine
to complete a 9-kilometer tunnel

29. The impact of tunnel diameter on the performance of TBMs in hard rock
D
TBM=15m
Comparison of the construction
schedule of the tunnel

30. The impact of tunnel diameter on the performance of TBMs in hard rock
Comparison of the construction
schedule of the tunnel
Performance parameters estimated for a 15m diameter single
shield machine to complete a 9-kilometer tunnel
1081 Days

31. The impact of tunnel diameter on the performance of TBMs in hard rock
D
TBM=15m
Comparison of the construction
schedule of the tunnel
Construction schedule and tunnel activities estimated for a 15m diameter single shield machine
to complete a 9-kilometer tunnel

32. The impact of tunnel diameter on the performance of TBMs in hard rock
Comparison of the construction
schedule of the tunnel
D
TBM=5m D
TBM=15m

33. The impact of tunnel diameter on the performance of TBMs in hard rock
Comparison of the construction
schedule of the tunnel
1081 Days518 Days

34. The impact of tunnel diameter on the performance of TBMs in hard rock
Adverse geological conditions

35. The impact of tunnel diameter on the performance of TBMs in hard rock
Adverse geological conditions

36. The impact of tunnel diameter on the performance of TBMs in hard rock
Adverse geological conditions
list of recent mechanized tunnels
constructed in Iran along with
identified faults

37. The impact of tunnel diameter on the performance of TBMs in hard rock
Adverse geological conditions

38. The impact of tunnel diameter on the performance of TBMs in hard rock
Adverse geological conditions
Zagros water conveyance
tunnel (2A)
Gomrood water conveyance
tunnel (3,4)

39. Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock
Schematic views and sample pictures of the potential for problems such as a, b) instability and roughness of the
tunnel face, c) water inflow in karstic zones and 4) roof and wall collapse, in fault zones

40. Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock
Preliminary proposed classification of fault zones
hazard in mechanized tunneling projects
In this study, 5 different factors which affect the occurrence of various geologic
hazards, have been used to classify the fault zones along the mechanized
tunnels. These factors include:
1)lithology,
2)overburden,
3)water pressure head,
4)discontinuities conditions and
5)faults specifications.
for each of the 4 geologic hazards, an index and a
separate equation is provided to determine their
relative occurrence potential. These 4 indices can be
used as criteria for classifying fault zones in three
categories: 1) the good, 2) the bad and 3) the ugly
(very bad) faults.
The variation range of each of the introduced criteria for a fault is between 0
and 10. The bigger these criteria are for a fault zone, the greater the risk and
the more negative effect of that fault zone on tunneling activities. The values of
all these 4 criteria in good faults should be less than 6. In ugly faults, the value
of at least one of these criteria should be greater than 8.

41. Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock

42. Gripping force of an open TBM and
resulting loads on the rock as a function of
the cuttability and the diameter of the TBM
Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock
Gripping force limitations

43. Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock
Squeezing potential

44. For a given rock formation the stability of the
tunnel is strictly dependent from the tunnel
diameter. For tunnel diameters more than 9 to 10
m there are virtually no rock formations that can
grant the full stability at short term. Even in the
best and harder rock blocks and debris fall down
from the tunnel walls immediately behind the
TBM cutterhead and require systematic support.
Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock
Tunnel stability

45. Adverse geological conditions
The impact of tunnel diameter on the performance of TBMs in hard rock
Tunnel stability

46. Adverse geological conditions
Influence of tunnel size on stability
The impact of tunnel diameter on the performance of TBMs in hard rock
Tunnel stability

47. For large and critical infrastructure projects, despite the progresses of the TBM technology made in the last years, it
can be convenient to execute an exploratory tunnel in advance. This particularly for long, large diameters tunnel
projects in complex and/or unknown geological conditions under high overburden
Exploratory Tunnels
The impact of tunnel diameter on the performance of TBMs in hard rock
Necessity of geological investigations
Although good progress has been made in the manufacturing of tunnel boring machines, there are still geological
conditions that, especially for large diameter TBMs, can put at risk the success of their implementation. For
important projects that foresee long and large diameter tunnels under critical and/or uncertain geological conditions
it is still advisable and profitable to anticipate the execution of an exploratory tunnel

48. An exploratory tunnel brings several advantages to the subsequent execution of the larger main tunnel and in
particular allows to:
•Drain the water in the area of the main tunnels to be executed;
•Provide with a full scale geological investigation;
•Reduce substantially the need and cost of other geological investigation campaign;
•Give important indications about TBM excavation parameters to be utilized in the design of the large diameter tbms;
•Reduce the prices offered by the bidding contractors due to the full knowledge of the geology;
•Treat in advance faults/adverse ground sections;
•Optimize the main tunnels support and lining system dimensioning;
•Reduce drastically the possible claims and litigations with the contractor and the consequent savings;
•Provide an additional access that an be utilized as service tunnel during the construction of the main tunnels
Exploratory Tunnels
The impact of tunnel diameter on the performance of TBMs in hard rock
Necessity of geological investigations
•؛یلصا لنوت ریسم رد ینیمزریز بآ راشف شهاک و هیلخت
•ۀئارا نیمز تاعلاطای سانش؛ییاسانش یاه شور ریاس ماجنا هنیزه و زاین شهاک و دهد یم هئارا لماک سایقم رد
• اب یرافح یاهرتماراپ دروم رد مزلا تاعلاطا ندومن مهارفTBM یحارط رد تسا مزلا هکTBM ؛دنریگ رارق هدافتسا دروم گرزب رطق اب یاه
• طسوت یداهنشیپ یاه تمیق شهاکناراکنامیپ نیمز زا لماک یهاگآ لیلد هب رازگ هصقانمی سانش؛یلصا یاه لنوت ریسم
•؛اهنآ زا روبع یارب مزلا یاهراکهار عقوم هب و حیحص باختنا و ییاسانش نیمز بولطمان طیارش و اهلسگ ینیب شیپ
•؛یلصا لنوت ییاهن ششوپ و یرادهگن متسیس داعبا و عون یزاس هنیهب
• و اهاعدا دیدش شهاک یواعد؛نآ بقاعتم یاه ییوج هفرص و راکنامیپ اب یلامتحا
•دریگ رارق هدافتسا دروم یلصا یاه لنوت تخاس لوط رد یتامدخ لنوت کی ناونع هب دناوت یم هک دنک یم مهارف ار یفاضا ی سرتسد.

49. Thank you