TBM Design and Tunnel Construction: Investigation & Exploration

This report provides an investigation and exploration of tunnel boring machines (TBMs) and tunnel construction methods. It discusses the design of cutter heads for hard rock boring, TBM working principles, and the impact of altitude on TBM performance. The report also examines control systems for monitoring TBM operations and proposes advanced tunnel modeling approaches to overcome current challenges. It highlights the importance of investigating TBM design and construction to avoid errors and reduce risks, advocating for new TBM designs that break from traditional paradigms. The study reviews existing literature, identifies gaps in research, and emphasizes the need for integrating external factors into TBM design to enhance operational efficiency. The report concludes by addressing the necessity for continuous innovation in TBM technology to meet the evolving demands of underground infrastructure projects.

INVESTIGATION OF DESIGN AND EXPLORATION OF A TUNNEL BORING MACHINE
AND TUNNEL CONSTRUCTION
BY
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Table of Contents
LIST OF FIGURES.........................................................................................................................2
GLOSSARY....................................................................................................................................4
EXECUTIVE SUMMARY.............................................................................................................5
INTRODUCTION...........................................................................................................................6
OBJECTIVES..................................................................................................................................7
LITERATURE REVIEW................................................................................................................8
Introduction................................................................................................................................8
Designing Cutter-heads for Hard Rock Boring......................................................................9
TUNNEL BORING MACHINE DESIGN.............................................................................10
Tunnel-boring machine performance Prediction..................................................................11
TUNNEL BORING MACHINE WORKINNG PRINCIPLES...........................................12
Altitude variation of tunnel boring machine.........................................................................13
Control devices and systems....................................................................................................14
Starting and stopping of the Control Unit.........................................................................15
TUNNEL CONSTRUCTION DESIGNS...............................................................................15
General design considerations................................................................................................16
THEORY.......................................................................................................................................16
Experiment and Equipment....................................................................................................16
TBM performance parameters...........................................................................................16
Penetration per revolution......................................................................................................17
RESULTS AND DISCUSSION....................................................................................................20
CONCLUSION..............................................................................................................................20
REFERENCES..............................................................................................................................20
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LIST OF FIGURES
Figure 1: Driving System for Cutter Head..................................................................................6
Figure 2: Tunnel Boring Machine Header................................................................................11
Figure 3: Cutter Head.................................................................................................................13
Figure 4: Analysis of TBM performance parameters..............................................................17
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GLOSSARY
TBM - tunnel boring machine
CDS - cutter head driving system
VC - vector control
TCS - torque control
VFD - Frequency Drive
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EXECUTIVE SUMMARY
A tunnel boring machines (TBMs) are heavy duty construction equipment that are used for
tunnel boring constructions. A tunnel is a closed way through which an obstacle is carried
through. Tunnel boring machines are vital tools used in underground infrastructural project.
There is an ever increasing awareness of the profits of the tunnel boring machines. Historically,
tunnel boring machines have always been used for construction of water diversion channels,
roads, drainages, conveyance etc. tunnel excavation is a complex and risky procedure and in
recent years major technical advancements have been made so as to improve the design and
efficiency of TBMs. These machines are based on old designs of more than 50 years ago are
majorly characterized by huge dimensions and enormous weights and high power consumption.
The cost of maintenance can be incredibly high. Replacement costs and technical assistance cost
are normally high due to the limited number of trained technical staffs. Recent major technical
advances have been developed for TBMs to enhance future considerations in excavation of
tunnels for complex mining procedures and layouts, (Yazdani-Chamzini, A. and Yakhchali, S.H.,
2012). On this note it is important that tunnel boring machines and tunnel construction be
properly investigated so as to avoid unnecessary errors and reduce risks during tunnel
construction. There is need to come up with new TBM designs that will break up the old
paradigms and allow for the design and exploration of new designs of developing TBMs and
new mechanisms and regulations of constructing tunnels. It is therefore necessary that in the
changing technological age, we do not have to limit ourselves to the old designs of TBMs. This
project is concerned with exploring various designs and operating conditions of tunnels.
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INTRODUCTION
Tunnel boring machines are high tech equipment that are used in construction projects because
of its many benefits in environment conservation projects. A tunnel is an underground passage
that is used for passage of trains, people and vehicles. It may also be an underground mining
passage.
The most important element of a tunnel boring machine is called the cutter head. The cutter head
is used to crush the ground with its powerful discs, (Huo et al 2012). It is operated by a cutter
head driving system (CDS). A cutter driving system is a complicated system that is mainly
compose of motors, pinions and ring gears.
The cutter driving system works by supplying torque to the cutter head through ring gears. The
more the driving torque is increased, the more the cutting power. T alter the torque power
depending on the load, the cutter driving system has a vector control (VC) and torque control
(TCS) system that are often applied to make or alter inverter responses to alter the torque as
required.
Figure 1: Driving System for Cutter Head
A TBM cutter head and its driving system often suffer a great load fluctuation which may reduce
its working condition during tunnel construction, (Liu, H., Li, P. and Liu, J., 2011). The gear
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transmission system may also be limited in working performance due to tear and wear, stiffness,
backlash and or transmission errors. These often results excessive damage and often failures.
There are few conditions under which cutter head can fail. Failure often occurs due to vibrations
and shock. To cut down the system vibration, a coupling model approach of a CD s is used to.
analyze dynamic characteristics of the system. Current technologies that have been used to
reduce these failures include using non-linear models of CDs and using non-linear gear meshing
factors, for example the time variant transmission gears, (JAVAD, G. and NARGES, T., 2010).
Changing geological factors and the Cutter Driving System are one of the few factors that impact
the failure of the Cutter head. These leads to excessive tear and wear, torque imbalance, gear
tooth breakage. Hence, to curb these problems, there needs to be an earnest investigation of the
design, the gear transmission system and the operating conditions of inverter motors.
This particular project is aimed at establishing an appropriate tunnel boring machine operating
conditions.
OBJECTIVES
1. To investigate the operation principles and efficiency of tunnel boring machines.
2. To investigate the impact of TBMs on underground transportation.
3. To analyze the usage of control systems to monitor TBM operations.
4. To investigate how altitude affects the working of TBMs.
5. To come up with more advanced and efficient tunnel modelling approaches as to overcome
current challenges.
LITERATURE REVIEW
Introduction
Tunnel boring machines are often used for urban tunneling especially those with a length of over
1.5 km. Applications of TBMS however requires careful considerations. Application of TBMs
for mining and municipal projects requires careful considerations, many which are technical and
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some non-technical. Wherever TBMs have been applied, one thing can be recognized – every
tunnel project and site location is unique in terms of access, geology, terrain and project
completion expectations and demands. Due to the varied needs of different sites, the design and
operation of TBMs needs to be carefully considered. There also needs to be a careful
consideration of the tunnel construction requirements, and apply them properly to the state of the
TBMs. It is the purpose of this paper to give an exposition of the design of TBMS and tunnel
construction considerations. Related work that has been done before on the technical
considerations of TBMs and tunnel construction include the following. (Yazdani-Chamzini, A.
and Yakhchali, S.H., 2012), designed a model for gear driving system and they investigated of
inertia on load-sharing characteristics.
Zhang et al. analyzed the characteristic of a tunnel boring machine (TBM) in mixed face
conditions.
Quin and Zhao came up with an optimization model for dynamic analysis and optimization of
the control motor. They came up with a control method to reduce vibration on the gear
transmission system.
While all these researches have made significant contributions aimed at improving the working
efficiency of TBMs, fewer researches have suggested new designs of TBM. Most designs are
based on the old paradigms of designing TBMs and there is need t come up with new designs
that will revolutionize the way TBMs are manufactured and even maintained. There is still
limited study on this subject since the cutter heads designs and variations are developed by
designers. Furthermore, designing of cutter heads involves complex algorithms developed by
manufacturers. To end users, the design of TBMs has been obscure to them, and their choice of
TBMs will be limited.
The studies that have been done in the recent years have not made significant engineering
propositions to improve the efficiency of TBMs, yet these studies have not fully addressed the
external factors that could be integrated into the TBMs design to increase its operation
efficiency. In this paper, explicit investigation of the design of TBMS will be made and a proper
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model will be developed that will be used in the design of more efficient TBMs, (Sun et al 2011).
Several elements that contribute to the efficient functioning of TBMS will be looked at, that
include influence of attitude to working efficiency of a TBMs, and the integration of an
Integrated Control System to manage the CDS.
Designing Cutter-heads for Hard Rock Boring
The efficiency of a tunnel boring machine depends much on many factors which include the
entire functionality of all system components and the entire rolling stock. The cutter head
however plays the most important role in the CDs, (Entacher, M., Lorenz, S. and Galler, R.,
2014). Therefore, the cutter head design is key to the operation of the CDs. Overly, the cutter
head designs greatly impacts rate of operation (ROP) and daily advance rate. (AR).
To increase the stability of the TBM in a rocky site, the may be need to use a double shielded
TBM, that will well endure the immense vibrations from such a site.
The cutter discs length and tonsil strength are often varied according to the power of a TBM. In
improved and more powerful TBMs, the enduring strength of the blades is generally high as
opposed to low power TBMs, (Font-Capó et al 2012). In dealing with the stiffness of hard rocks,
the torque is of necessity to be high so as to withstand the reaction from hard surfaces.
TUNNEL BORING MACHINE DESIGN
A generic TBM is made of a cutting head which is composed of cutting discs as shown in Fig
two below. The cutting disc can be up to 8 meters in diameter. The cutting discs increase the
efficiency of the cutter head, (Peila et al 2011).
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Figure 2: Tunnel Boring Machine Header
Tunnel-boring machine performance Prediction
The cutting discs that a cutting header has dictate the overall performance of a TBM. Using the
linear cutting test of a TBM, various variables established through the operation of the machine
can be determined. (Yagiz et al 2009). The main element in the linear cutting test is the space
that needs to be between any two cuts. The linear cutting test majorly helps in determining
external factors that may be considered to increase the efficiency of the TBM. Cutting forces
may also vary depending on the type of tunnel and kind of soil in the construction site. .
Furthermore, the TBMS calls for many other external features that would increase its efficiency
too. The linear cutting test majorly helps in determining external factors that may be considered
to increase the efficiency of the TBM. Cutting forces may also vary depending on the type of
tunnel and kind of soil in the construction site.
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To measure the cutting forces, the load shell helps and also gives TBM operators ability to alter
operating speeds of the cutting blades and therefore control the cutting process.
The discs need to be positioned in a certain position in order to achieve grater cutting depths. In
order to achieve the desired function, the cutting force should always be applied perpendicular to
the rolling direction, (Jiujiang, C.U.I., 2009 ).
The energy considerations of the machine include torque and power requirements as needed by
the machine. These conditions need be established in order to determine specific energy required
by a TBM, ( Li et al 2008 ).
TUNNEL BORING MACHINE WORKINNG PRINCIPLES
In order for a TBM to achieve its working efficiency three combinations. The cutter-head ought
to have bracing systems operated by a hydraulic system to ensure efficiency a TBM. Moreover, a
central conveyor system should be installed to remove source chips from the source. The cuter
head is shown in the figure below:
Figure 3: Cutter Head
In order for the head source to rotate at 360 degrees, several discs interlock with one another,
which leads to an increase in penetrating force of the TBM. The surface gets loosened as the
TBM penetrates.
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Altitude variation of tunnel boring machine
A TBM works differently on different occasions, depending on various factors. A tunnel boring
machine will always show different characteristics in different conditions. In connection, its
performance is affected too. The machine tends to advance into the ground more in low altitudes
than in higher altitudes, (Sousa, R.L. and Einstein, H.H., 2012 ). This can easily be proved in the
boring of granite. Understanding the forces that the machine will counter is important in
determining the type of cutters that must be used. For example a generic tunneling machine
would work more efficiently in low altitude areas because of the weak forces that the machine
will have to encounter. Many operators of TBMs would therefore prefer low altitude to high
altitude areas.
Control devices and systems
Control systems play a very important role especially to monitor working of a conveyor belt.
Controlled monitoring will ensure that risks are properly mitigated and even eliminated.
Therefore, there must be established regulations that should be set to monitor the installation and
maintenance of the control system, (Mengshu, W.A.N.G., 2008 ). These may include the
following:
i. The control system should be properly labeled and should be visible and easily
identifiable.
ii. They should be positioned for safety operations so as to avoid unnecessary actuations.
iii. They should be located next to one another if the start and stop functions are not
located on the same controlling device.
iv. They should be guards on each controlling system so as to avoid unnecessary
actuations.
The control, systems should be designed such that:
i. The hydraulic pumps that switch the drive motors shall not cause danger to other
machines or persons.
ii. There shall be no danger in case the voltage control fails.
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