Conference PaperPDF Available

Project control by using the NTNU model methodology: The new Ulriken Tunnel

Authors:
  • JMConsulting-Rock Engineering AS
  • Bane NOR SF

Abstract and Figures

The Tunnel Boring Machine (TBM) method has become a widely used method for hard rock tunnelling. The use of TBMs involves major investments and high levels of geological risk, furthermore, the method requires accurate predictions of TBM performance and costs in order to facilitate the control of risk and enable projects to avoid delays and budget overruns. During tunnel excavation, a detailed follow up of the TBM performances through laboratory testing, geological mapping and TBM data is required. The NTNU model methodology can be a practical and reliable tool for execution control avoiding tedious and costly disputes. The paper describes the applicability of the NTNU model methodology used for project management for parties, client and contractor, in a running TBM tunnel: The New Ulriken Tunnel.
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Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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1 INTRODUCTION
The use of hard rock tunnel boring machines
(TBMs) has become widely and generally used
with success.
Hard rock tunnel boring involves major
investments and high levels of geological risk,
which require reliable performance predictions
and cutter life assessments; unfortunately, in too
many cases, due to unanticipated situations and/or
inappropriate assessments, with undesirable
consequences.
Hard rock tunnel boring leads the interaction
between the rock mass and the machine, which is
a process of great complexity. The tunnelling
system around the excavation process has a great
relevance in the final goal of performance
predictions for hard rock TBMs, which is the
estimation of time and cost.
For the New Ulriken tunnel project, a TBM
was chosen to excavate approximately 7
kilometres, through a geology dominated by
metamorphic igneous rock.
The tunnel is being excavated and built by
the contractor Joint Venture Skanska Strabag,
on behalf of the client Bane NOR (Previously
the Norwegian National Rail Administration).
The paper describes the applicability of the
NTNU model methodology used for project
management for parties, client and contractor, in
a running TBM tunnel: The New Ulriken
Tunnel.
During tunnel excavation, a detailed follow
up of the TBM performances through laboratory
testing, geological mapping and TBM data is
required and is carried out at New Ulriken
tunnel. The NTNU model methodology can be a
practical and reliable tool for execution control
avoiding tedious and costly disputes (Macias,
2016).
A comprehensive understanding of the rock
mass boreability requires different approaches
to its evaluation. Continuous geological back-
mapping supported by laboratory testing, tunnel
face inspection and chip analysis is used.
In addition, field trials involving two types of
test; (1) the commonly used penetration test and
(2) the so-called ‘RPM test’ introduced by
Macias (2016), are performed. The main
purpose of performing field trials and tests is to
evaluate machine performance under a given set
of geological conditions.
Project control by using the NTNU model methodology: The new
Ulriken Tunnel
F. J. Macias
SINTEF, Trondheim, Norway / NTNU, Trondheim, Norway
T. Andersson
Skanska-Strabag, Bergen, Norway.
L.N.R. Eide
Bane NOR, Bergen, Norway.
ABSTRACT: The Tunnel Boring Machine (TBM) method has become a widely used method for
hard rock tunnelling. The use of TBMs involves major investments and high levels of geological
risk, furthermore, the method requires accurate predictions of TBM performance and costs in order
to facilitate the control of risk and enable projects to avoid delays and budget overruns.
During tunnel excavation, a detailed follow up of the TBM performances through laboratory
testing, geological mapping and TBM data is required. The NTNU model methodology can be a
practical and reliable tool for execution control avoiding tedious and costly disputes.
The paper describes the applicability of the NTNU model methodology used for project
management for parties, client and contractor, in a running TBM tunnel: The New Ulriken Tunnel.
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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2 THE NEW ULRIKEN TUNNEL
The new Ulriken tunnel is situated between the
city of Bergen and Arna (Part of Bergen
municipality) on the railway line
“Bergensbanen” which stretches between Oslo
in the east and Bergen in the west. This new
tunnel will be a parallel tube to the already
existing Ulriken tunnel, which was excavated by
Drill and Blast and opened for traffic in 1964.
The new tube will be 7.8 kilometres long,
and for the first time in the history of
Norwegian railroad tunnelling, a TBM was
chosen to excavate the major part of this tube.
While approximately 800 meters was excavated
by Drill and Blast, a 9.3 meter diameter TBM
has started excavating the remaining 7
kilometres. At the start of excavation, this was
also the largest TBM ever used in Norway.
The new tube runs south of the existing tube
and the distance between the two tubes varies,
but in most parts the distance is approximately
35-40 meters. The new tube ascends at a
gradient of 0.88 % the first 1.9 km from the
east, and descends to the Bergen side at a
gradient of 0.30 % for the remaining distance.
The geology of the drive is dominated by
metamorphic igneous rock.A cross section of
the expected geology is show in Figure 1.
Starting from the Arna side, the rock types
encountered are granite, syenite, monzonite,
charnockite and granulite, before anorthosite
and granitic gneiss are found. The middle part
of the drive consists of augen gneiss and banded
gneiss, migmatite, migmatic gneiss, quartzite
and quartzitic schist. The western part towards
Bergen contains amphibolite, gabbro,
greenstone, mica schist and mylonitic gneiss.
The overburden of the rock varies between
the minimum of 5 meters to the maximum of
600 meters.
Figure 1. Geological cross section between Bergen and
Arna (Fossen and Ragnhildstveit, 2008).
The expected fracturing in the tunnel is steep and
in normally almost perpendicular to the tunnel axis,
which is considered to be very beneficial for TBM
tunnelling (Bruland, 2000).
Figure 2. Orientations of all mapped discontinuities
(Norconsult, 2013).
The TBM used for the drive is manufactured by
Herrenknecht, and the most important technical data
from the TBM is given in the table below:
Table 1. Technical specifications Herrenknecht TBM S-
935 (Herrenknecht, 2014)
Parameter Value
TBM diameter 9.33
m
N
umber of cutters 62
Cutter diamete
r
483 mm (19")
N
ominal thrust force 27 500 kN
Cutterhead rotation spee
d
0
6.4 rev/min
Stroke length 2.0
m
Cutterhead weigh
t
223 ton
Weight with bac
-up 1 800 ton
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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Figure 3 shows the TBM during the assembly
at the tunnel portal in Arna (Norway).
Figure 3. The TBM assembled at New Ulriken tunnel site
in Arna (Norway).
The tunnel is excavated and built by the
contractor Joint Venture Skanska Strabag, on
behalf of the client Bane NOR (Previously the
Norwegian National Rail Administration). The
design team for the TBM part of the project has
been Norconsult AS and Basler & Hofmann
AG. The TBM is scheduled to break through in
the last half of 2017.
3 THE NTNU MODEL METHODOLOGY
3.1 General
The philosophy of the NTNU model is to
achieve reliable predictions by combining
relevant rock properties and machine
parameters. Several steps are involved in the
NTNU prediction model for hard rock TBMs in
order to estimate time and costs involved in
tunnel excavation using factors such as: net
penetration rate, cutter life as well as advance
rate and excavation costs. The NTNU models
used to estimate hard rock tunnelling,
penetration rate and cutter life provide reliable
and practical tools for:
o estimating net penetration rate and cutter
wear
o estimating time consumption and exca-
vation costs, including risk
o assessing risk linked to variation in rock
mass boreability and machine parame-
ters
o establishing and managing contract price
regulation
o verifying machine performance
o verifying variation in geological condi-
tions
The models can be used, at various stages of
a given project:
Preliminary and feasibility studies
Evaluation of the excavation method
Project design and optimisation
During tendering and contract processes
Documentation during construction
Possible disputes and claims
The models are based on project site studies
and statistics derived from more than 40
tunnelling projects carried out in Norway and
abroad, involving more than 300 kilometres of
tunnel. The data have been systematised and
normalised and the results are regarded as being
representative of well-organised tunnelling
projects.
The model has been the subject of continuous
development a successive development since
the first version was published in 1976 by the
NTNU (formerly NTH). A last version of the
model has recently been published (Macias,
2016).
4 UNDERSTANDING ROCK MASS
BOREABILITY
An evaluation of the influence of rock mass on
the TBM tunnelling process is not always easy
or straightforward. A comprehensive
understanding of the rock mass boreability
requires different approaches to its evaluation. It
is recommended here that both chip analysis and
tunnel face inspection should be used to support
engineering geological back-mapping (Macias,
2016).
Figure 4 shows a schematic outlining different
the approaches to the understanding of rock
mass boreability in connection with hard rock
TBM tunnelling.
Tunnel face inspection enables the identification
of fractures that influence the rock breaking
process, and the voids formed following the
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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breaking process as determined by the presence
of fractures. Continuous tunnel face inspection
should be a part of the geological back-mapping
methodology.
The presence of voids implies that a few cutters
have lost contact with the face during
tunnelling, transferring the load to other cutters.
This will result in a dynamic effect during the
breaking process and therefore in an increase of
the penetration rate. Moreover, the relative
orientations of the fractures in relation to the
tunnel direction result in different void sizes.
Figure 4. Schematic outlining different approaches to the
understanding of rock mass boreability in connection with
hard rock TBM tunnelling (Macias, 2016).
Laboratory testing assessing the intact rock
properties needs is performed in parallel to the
approaches to the understanding of rock mass
boreability,
4.1 Drillability
There are several methodologies available to
assess the influence of intact rock properties in
hard rock tunnel boring. Following, the main
intact rock properties and commonly used test
methodology are listed:
- Strength testing: Uniaxial Compressive
Strength (UCS), Brazilian Tensile
Strength (BTS), Point Load Test (PLT).
- Surface hardness: Sievers’ J miniature drill
test (SJ), Vickers hardness (VH).
- Brittleness: brittleness tests (S20), several
definitions including: strain, UCS and
tensile strengths, stress-strain relations.
- Abrasivity: Cerchar test (CAI), LCPC test,
Abrasion Value Steel test (AVS), abra-
sive minerals content, Vickers hardness
number of rock (VHNR).
- Rock petrography (rock texture, mineral
composition).
The Drilling Rate Index (DRI) and Cutter
Life Index (CLI) have been selected as the
drillability parameter for intact rock in the
NTNU/SINTEF methodology.
DRI is a laboratory index for the indirect
measurement of intact rock boreability
(drillability). The higher the DRI, the higher the
drillability. It is an indirect measure of the
breaking work required and an effective gauge
of the rock-breaking process under a cutter disc
and is defined as the brittleness value adjusted
for surface hardness. The brittleness test is
believed to crush the rock mostly by induced
tension in an ‘instant’ process due to impact
loading). The brittleness value (S20) expresses
the amount of energy required to initiate and
crush the rock. Finally, the DRI is obtained
from the S20 adjusted for rock surface hardness
(SJ).
CLI expresses life in boring hours for cutter
disc rings of steel for tunnel boring machines.
Figure 5 is a schematic representation of the
brittleness value (S20) and Sievers J-value (SJ)
in the breaking process under a cutter disc in
hard rock.
The NTNU/SINTEF drillability test method
has gained international recognition.
Nonetheless, there are only a few laboratory
facilities in the world that are able to reproduce
these tests as opposed to other more commonly
used test methodologies such as UCS and BTS.
There are however, besides located in Norway,
some other laboratories worldwide, in Australia,
South Korea, Spain, South Africa, Turkey and
USA, which possesses the necessary equipment.
The trademark acronyms and terms relating to
the indices DRI™ (Drilling Rate Index™) and
CLI™ (Cutter Life Index™) are however
unique to test results originating from the
NTNU/SINTEF laboratory in Trondheim
(Norway).
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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Figure 5. Schematic representation of the brittleness value
(S20) and Sievers J-value (SJ) in the breaking process
under a cutter disc in hard rock (Macias, 2016).
Continuous laboratory testing has been
performed along the analysed tunnel sections at
New Ulriken project.
Table 2 shows the range of values of the
laboratory testing carried out.
Table 2. Laboratory testing at New Ulriken tunnel
Laboratory
t
es
t
Value
UCS (MPa) 58 – 281
DRITM 33 – 55
CLITM 3.5 – 23.3
CAI 3.6 – 5.4
Quartz content (%) 4 - 32
The rock types in terms of rock strength
using the Uniaxial Compressive Strength (UCS)
and according the ISRM (1978) are classified as
between 'high' and 'extremely high strength'.
The drillability indexes, Drilling rate index
(DRITM) and Cutter Life Index (CLITM), are
classified between 'extremely low' and 'high' an
according to Macias (2016).
Cerchar Abrasivity Index (CAI) is classified
between 'high' and 'extremely high' according to
ISRM (2014).
Several quartzite intrusions appear
intercalated.
4.2 Geological back-mapping
The process of tunnel back-mapping consists of
the continuous and detailed mapping of rock
mass fracturing and rock type distribution, rock
sampling, and the subsequent laboratory testing
of rock properties. The purpose is to establish a
geological model of the tunnel that can then be
used for the evaluation of machine performance,
machine utilisation, trials, cutter life and other
factors.
The engineering geological back-mapping
procedure employed during this study is based
on the NTNU approach (Bruland, 2000; Macias,
2016), and consists of the following steps:
- Determination of rock type
- Identification of the strike and dip of
Marked Single Joints
- Notes on other singular phenomena such as
intrusions, mixed face, water, rock sup-
port, etc.
- Determination of the number of fracture
systems for each system
- Measurement of the strike (αs) and dip (αf)
of the fracture system(s)
- Measurement of the strike (azimuth) of the
tunnel (αt)
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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Figure 6 shows an example of geological
back-mapping carried out in the New Ulriken
tunnel.
Figure 6. Example of geological back-mapping carried
out in New Ulriken tunnel.
If the principal classes listed in Table 3 are
inadequate for a detailed description of fracture
spacing, intermediate classes could also be
included for practical mapping purposes.
Rock mass properties for TBM tunnelling are
expressed by the equivalent fracturing factor
(kekv).
porDRItotsekv kkkk
where
k
ekv = equivalent fracturing factor
k
s-tot = total fracturing factor
k
DRI = correction factor for the DRI of the
rock
k
por = correction factor for the porosity of
the rock
Rock mass boreability is expressed by the
fracturing factor (ks), which is dependent on the
degree of fracturing and the angle between the
tunnel axis and the planes of weakness (α) in
systematically fractured rock masses.

arcsin ( sin )
fts
sin


where
αs = strike angle of the planes of weakness
αf = dip angle of the planes of weakness
αt = azimuth of the tunnel axis
The fracturing factor is obtained as a function
of fracture class and the angle between the
tunnel axis and systematic fractures (Macias,
2016).
For more than one set of fractures, the total
fracturing factor will be as follows:

1
10.36
n
stotavg si
i
kkn


where
k
s-tot = total fracturing factor
k
si = fracturing factor for set no. i
n = number of fracture sets
A maximum of three fracture sets (n=3) is
recommended, possibly with one or two main
sets and one set including the random fractures.
It is important to include all the fractures in the
rock mass interpretation, i.e. random fractures
(except marked single joints, MSJ).
The value of ks-tot should not exceed 4 since
this will be outside the model range.
The fracturing factor (ksi) is calculated for
each section of tunnel.
Table 3 presents a summary of fracture class
terminology as defined by the average spacing
between fractures.
Table 3. Fracture class terminology as defined by the
average spacing between fractures (Macias, 2016).
Fracture
Class
(Sf)
Average
spacing
between
fractures
af(cm)
Range class
(cm)
Degree of
fracturing
0480
N
on-fracture
d
1 320 240
480 Extremely low
2 160 120
240 Ver
y
low
38060
120 Low
44030
60 Mediu
m
52015
30 Hi
g
h
6107.5
15 Ver
y
hi
g
h
754
7.5 Extremely high
Figure 7 presents the fracture class
distribution along approximately 700 m TBM
tunnel section at New Ulriken tunnel.
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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Figure 7. Example of frequency distribution of fracture
classes along approximately 700 m TBM tunnel section at
New Ulriken tunnel.
Figure 8Error! Reference source not
found. shows the fracturing factor (ks)
distribution along the approximately 700 m
TBM tunnel section at New Ulriken tunnel.
Figure 8. Fracturing factor (ks) distribution along
approximately 700 m TBM tunnel section at New Ulriken
tunnel.
4.3 Tunnel face mapping
Tunnel face inspection enables the identification
of fractures that influence the rock breaking
process, and the voids formed following the
breaking process as determined by the presence
of fractures. Continuous tunnel face inspection
is a part of the geological back-mapping
methodology.
Figure 9 are two photographs taken during a
tunnel face inspection showing different
fractures that may have different levels of
influence on the rock breaking process due to
their respective orientations.
Figure 9. Photography of tunnel face mapping at New
Ulriken tunnel.
The presence of voids implies that a few cutters
have lost contact with the face during
tunnelling, transferring the load to other cutters.
This will result in a dynamic effect during the
breaking process and therefore in an increase of
the penetration rate. Moreover, the relative
orientations of the fractures in relation to the
tunnel direction result in different void sizes
4.4 Rock chipping analysis
In addition to tunnel face inspection, chip
analysis provides information relevant to boring
efficiency. It may also be a valuable tool that
can contribute towards the understanding of the
rock boreability of a given rock mass.
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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Inspection of rock chips may enable us to
identify and/or measure the variation in shear
strength properties along a given plane of
weakness and the possible influence on intact
rock and the rock mass as a whole.
The stress field under a cutter edge, and how
efficiently it is utilised when boring, may be
studied indirectly by recording chip shape and
crack patterns (Bruland, 2000).
Figure 10 shows the characterization of the
largest chips by a shape factor.
Figure 10. Shape factors of chip analysis (Bruland, 2000).
The general trend is that the shape of the
chips moves from flat and elongated at low
thrust levels towards a more elongated, and
even more cubic shape at higher thrust levels.
Figure 12 shows an analysis of crack
propagation in a rock chip sample.
Figure 11. Crack analysis of a rock chip sample (Macias,
2016).
5 FIELD TESTING: PENETRATION AND
'RPM' TESTS
5.1 General
Field trials involves two types of test; (1) the
commonly used penetration test and (2) the so-
called ‘RPM test’ introduced by Macias (2016).
The main purpose of performing field trials
and tests is to evaluate machine performance
under a given set of geological conditions. Field
trials should be followed by detailed
engineering geological mapping and rock
sampling for drillability testing.
It is strongly recommended the inclusion of
test procedures both at the commencement of,
and during, TBM projects in order to select the
optimal operational parameters from among the
many options available for a given machine and
set of geological conditions (Macias, 2016).
5.2 Penetration tests
A penetration test consists of a measurement of
cutterhead penetration over a given time at a
variety of logged thrust levels carried out at
constant cutterhead velocity. The cutterhead
torque for each cutter load level is also noted.
Logging includes the measurement or
recording of net penetration rate, cutter thrust
level and cutterhead torque for the preceding
and subsequent strokes.
Other relevant data such as cutter wear state
and cutterhead vibration level are also recorded,
together with a note as to whether the test is
performed at the start, middle or end of the
stroke.
5.2.1 Penetration rate model.
The penetration rate model is based on
normalised penetration curves. The best fit to
these data is established to be a power function.
The model is based on the equation below (1)
for basic net penetration rate:
(mm/rev)
1
0
M
M
iekv
b
where
i
0 = basic penetration rate (mm/rev)
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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M
ekv = equivalent cutter thrust (kN/cutter)
M
1 = critical cutter thrust (kN/cutter, the
thrust required to achieve 1 mm/rev)
b = penetration coefficient
Penetration curves are found by processing
data recorded during penetration tests. A
penetration test involves a full-scale trial during
which thrust values are varied while cutterhead
velocity for a given geology is kept constant.
The critical cutter thrust (M1) and the
penetration coefficient (b) for a given geology
are found by regression from the penetration
tests.
5.3 RPM tests
Cutterhead velocity and the rolling velocity of
the cutters have a significant influence on
penetration rate.
A reduction in cutterhead velocity (rpm)
values may improve boring efficiency and
reduce excavation costs. Lower cutterhead rpm
will promote lower cutter rolling distances and
velocities for a given section of tunnel, resulting
in significantly higher cutter ring life and a
reduction in potential damage to cutters.
Moreover, for a given thrust level and fewer
revolutions of the main bearing reduce the
probability of bearing failure and cutterhead
damages, as well as energy consumption.
The loading rate of the cutter rings over a
given point of the rock face is proportional to
cutterhead rpm. The general rule in rock
mechanics testing is that the loading rate
influences the deformation and strength
properties of a rock sample. A higher loading
rate will normally result in higher rock strength.
The influence of rpm on penetration rate was
evaluated by means of full-scale trials of
specified cutterhead velocities. An ‘RPM test’
measures cutterhead penetration over a given
period at a variety of cutterhead velocities under
constant cutterhead thrust (Macias, 2016). The
aim of the test is to evaluate the influence of
cutterhead velocity (rpm) on penetration rate
(mm/rev) for maximum net penetration rates
(m/h) for a given machine, geology and thrust
level.
The trials revealed that in general, a lower
cutterhead velocity would result in an increase
in penetration rate up to a given value (Macias,
2016). The values concerned are dependent on
cutterhead design, rock mass properties and
level of thrust.
The resulting values obtained from the ‘RPM
tests’ include values of penetration rate (PR, in
mm/rev) and net penetration rate (NPR, in m/h)
for each cutterhead rpm at constant level of
thrust. These values are used to plot a trend line
from which calculations of the initial point of
the ‘RPM test’, optimal cutterhead velocity and
the corresponding penetration rate for the
recommended cutterhead velocity can be made.
5.3.1 Example of 'RPM test' at New Ulriken
tunnel
'RPM tests' are performed at New Ulriken
tunnel. The objective is to evaluate machine
performance under a given set of geological
conditions allowing the selection of optimal
operational parameters.
Table 4 shows the summary of the values
resulting from one the 'RPM tests' performed
during excavation at New Ulriken tunnel.
Table 4. Summary of the values of one of the 'RPM test'
carried out at New Ulriken tunnel. Cutter thrust 306
kN/cutter.
Cutterhead
velocity (rpm)
Penetration
rate
(mm/rev)
N
et
penetration
rate (m/h)
4 6.74 1.62
4.5 6.12 1.65
5 5.58 1.67
5.5 4.59 1.51
Analysing the 'RPM test' according to Macias
(2016), the maximum net penetration rate (m/h)
in the 'RPM test' (Figure 12) is achieved for 4.6
rpm and the 'optimal' rpm for 3.9.
Figure 12. 'RPM test' carried out at Ulriken tunnel
Proceedings of the World Tunnel Congress 2017 – Surface challenges – Underground solutions. Bergen, Norway.
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Figure 13 shows the normalised based on the
recommended cutterhead velocity for each TBM
diameter according to Macias (2016).
Figure 13. Normalised 'RPM test' at Ulriken tunnel
6 CONCLUSIVE REMARKS
The paper describes the applicability of the
NTNU model methodology used for project
management for parties, client and contractor, in
a running TBM tunnel: The New Ulriken
Tunnel.
The NTNU model methodology can be a
practical and reliable tool for execution control
avoiding tedious and costly disputes (Macias,
2016).
A comprehensive understanding of the rock
mass boreability requires different approaches
to its evaluation. During tunnel execution, a
detailed follow up of the TBM performances
through laboratory testing, geological mapping
and TBM data is required and it being carried
out at New Ulriken tunnel.
In addition, field trials involving two types of
test; (1) the commonly used penetration test and
(2) the so-called ‘RPM test’ introduced by
Macias (2016), are performed. The main
purpose of performing field trials and tests is to
evaluate machine performance under a given set
of geological conditions.
It is believed that by including this
requirement in project contracts, many tiresome
disputes can be avoided. Continuous trial testing
(penetration and ‘RPM tests’), combined with
descriptions of geology, drillability and rock
mass fracturing will enhance our knowledge of
the tunnel boring process.
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method. Tunnelling and Underground Space
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Fossen H. and Ragnhildstveit J. 2008. Geological Map
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Herrenknecht 2014. Project document: Technical
specifications and layout information TBM S-935,
Rev. 0 (08.09.2014)
ISRM International Society for Rock Mechanics. 1978.
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ISRM International Society for Rock Mechanics. 2014.
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no.1 (2014), pp 261-266.
Macias, F.J. 2016. Hard Rock Tunnel Boring:
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konkurransegrunnlag
... Specifically, field study can provide excellent evaluation of TBM performance-under the given geological conditions (Gong et al., 2007;Macias et al., 2017;Jing et al., 2019). However, the field study cannot be performed systematically under given TBM cutter head design and ground conditions. ...
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Underground research laboratory (URL) plays an important role in safe disposal of high-level radioactive waste (HLW). At present, the Xinchang site, located in Gansu Province of China, has been selected as the final site for China’s first URL, named Beishan URL. For this, a preliminary design of the Beishan URL has been proposed, including one spiral ramp, three shafts and two experimental levels. With advantages of fast advancing and limited disturbance to surrounding rock mass, the tunnel boring machine (TBM) method could be one of the excavation methods considered for the URL ramp. This paper introduces the feasibility study on using TBM to excavation of the Beishan URL ramp. The technical challenges for using TBM in Beishan URL are identified on the base of geological condition and specific layout of the spiral ramp. Then, the technical feasibility study on the specific issues, i.e. extremely hard rock mass, high abrasiveness, TBM operation, muck transportation, water drainage and material transportation, is investigated. This study demonstrates that TBM technology is a feasible method for the Beishan URL excavation. The results can also provide a reference for the design and construction of HLW disposal engineering in similar geological conditions. © 2020 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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Thesis
The use of hard rock tunnel boring machines (TBMs) has become widely and generally used with success but in too many cases, due to unanticipated situations and/or inappropriate assessments, with catastrophic consequences. Hard rock tunnel boring involves major investments and high levels of geological risk, which require reliable performance predictions and cutter life assessments. Hard rock tunnel boring leads the interaction between the rock mass and the machine, which is a process of great complexity. The tunnelling system around the excavation process has a great relevance in the final goal of performance predictions for hard rock TBMs, which is the estimation of time and cost. The overall aim of this thesis is to build on the existing knowledge of tunnel boring and wear processes, technology and capacity, thus enhancing performance prediction and cutter life assessments in hard rock tunnel boring projects. The prediction model for hard rock TBMs developed by the Norwegian University of Science and Technology (NTNU) is based on a combination of field performance data, engineering geological back-mapping, and laboratory testing. The development of TBM technology during recent decades, and the possible influence of parameters not considered in previous versions, has made revision of the model to improve prediction accuracy an essential requirement. TBM specifications, the penetration rate and cutter life models have been revised and extended to adapt to the current technology. In addition, it has been incorporated a new definition of the rock mass fracturing, the influence of the cutterhead velocity (rpm) on penetration rate on the in response to the results of in-situ trials 'RPM tests' and cutter thrust on cutter life. The tunnel length effect on time consumption for the tunnelling activities has been introduced for the estimation of the machine utilization and therefore in the advance rate model. A revised and extended version of the current version of the NTNU prediction model for TBM performance and cutter life has been published included in this thesis. Cutter consumption and parameters such as cutter ring wear play a significant role in performance and cost predictions, especially in hard rock conditions. Cutter wear involves a complex tribological system in interaction with the geological properties of the rock mass. Existing laboratory test methods fail to reproduce wear behaviour encountered during tunnel boring. Because of this, and the importance of cutter wear, it was considered of interest to develop a new rock abrasivity test method for tool life assessments in hard rock tunnel boring: The Rolling Indentation Abrasion Test (RIAT). Understanding the processes and failure mechanisms during cutter wear enabled new knowledge to be applied as part of the development of the new rock abrasivity test method for laboratory use. In addition, cutter wear mechanisms affecting cutter rings during tunnel boring might lead to better cutter consumption predictions and future improvements in cutter ring development.
Article
The demand for representative rock property parameters related to planning of underground excavations is increasing, as these parameters constitute fundamental input for obtaining the most reliable cost and time estimates. The Brittleness Value (S20), Sievers’ J-Value (SJ), Abrasion Value (AV) and Abrasion Value Cutter Steel (AVS) have been used extensively at NTNU/SINTEF since the 1960s in connection with drillability testing of rock samples. Nearly 3200 samples originating from projects in 50 countries have so far been tested, and the method and associated prognosis model are internationally recognised for giving reliable estimates of time and cost for tunnelling. A classification of the NTNU/SINTEF drillability indices Drilling Rate Index™ (DRI), Bit Wear Index™ (BWI) and Cutter Life Index™ (CLI) has been available since 1998, but until now no official classification has been available for the individual tests used to calculate these indices. In this paper, classifications of the NTNU/SINTEF drillability test methods Brittleness Value (S20), Sievers’ J-Value (SJ), Abrasion Value (AV) and Abrasion Value Cutter Steel (AVS) tests will be described in detail. The presented classifications of the individual tests are based on statistical analysis and evaluations of the existing test results recorded in the NTNU/SINTEF database.
Hard Rock Tunnel Boring Machines
  • B Maidl
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Maidl, B., Schmidz, L., Titz, W & Herrenknecht, M. 2008. Hard Rock Tunnel Boring Machines. Ernst and Sohn, Berlin. Norconsult 2013. Report UUT-00-A-12002, Ingeniørgeologisk -hydrogeologisk rapport for konkurransegrunnlag
Suggested methods for the quantitative description of discontinuities in rock masses
ISRM International Society for Rock Mechanics. 1978. Suggested methods for the quantitative description of discontinuities in rock masses. -Commission on Standardization of Laboratory and Field Tests, Document No. 4, International Journal of Rock Mechanics, Mining Science & Geomechanics Abstracts, 15: 319-368.
Geological Map Bergen 1115 I, M 1:50 000
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