my plan for dissertation last tunnel

“Fundamental Aspects of Design and Constructing Tunnel on Past, Present

and the Future”

Dana KadirBEng-Civil Engineer

University of CoventryAcademic year 2013-2014

Dissertation Supervisor: Dr Sam Ng’ambi

Abstract

Generally this dissertation project is going to cover major identification of the fundamental

aspects related to both design and construction of tunnelling. Alongside, looking back to the

history of tunnelling and how this structure is become more important and helping growth in

country. Furthermore, different types of soils and materials can be studied practically and in

research review from the past experience in order to comprehend the consequence of layers of

ground and materials of use to discover the right way to design and construct the tunnel. Finally

some of the most vital methods and technology for tunnel construction at present are deliberated

and the view future for tunnelling will be demonstrated.

The future of tunnelling needs more advanced and sophisticated monitoring and excavation

technologies together with superior construction measures and techniques to address various site

specific conditions

Contents

1 Intoduction

1. Introduction

1.1 History of Tunnelling

For years in mankind history, earth has been excavated and made caverns and tunnels for many

purposes of life. Almost every great development and civilization of mankind made interest of

digging and building tunnels, various type of digging and tunnelling were made in past for many

purposes of use for instance using for shelter or to store food. In very early time tunnels have

made in different kind of materials such as flint, wood, and later with improvement of people life

and increasing demands of using tunnels other material such as bronze, iron, steel and concrete

have used. From early time there is evidence with according to (Wahlstrom, 1973) that in Stone

Age human were sank shafts and drove tunnels in order to obtain flint for sharp edge tools. There

are a number of detailed histories and methods of constructing tunnel, some remained and others

demolished. According to (David chapman.2010) the earliest evidenced to construct the tunnels

using the gunpowder was for a pioneering tunnel of the canal age built on the Canal “du Midi”

which was constructed across France in the 1666-1681. The Canal du Midi was 157m long and

connected the Atlantic Ocean to the Mediterranean Sea and the tunnel was rectangular cross

section shape. Additionally, in the UK, the past engineering art has created magnificent channel

system which was part of the industrial revolution. For instance the Harecast Tunnel in 1770s was

2090m long constructed using gunpowder to bore the ground. Also within according to

(Chapman.2010) there has been substantial development in tunnel construction techniques in the

last two centuries particularly after first use of tunnelling shield under the River Thames in

London by Marc Brunel in 1825-1842. Whereas, the key role of this technique was to support the

face and provide safety for the workers by used cast iron shields. Figure () is demonstrated sample

details of this technique somehow its very similar to nowadays tunnel technique systems.

Figure () display details of Brunel’s Shield (Chapman.2010)

Extra infor from (Ref: Tunnel construction by David Chapman, Nicole Metje and Alfred

Stark.2010

Furthermore, the tunnel became very interesting in many other regions around world. In Europe

the first major construction of tunnel between two portals was built by using rock drills. At same

time in the USA the Hoosac Tunnel started at 1855 and it was 7.44km long, in order to increase

the rate of the Hoosac tunnel construction a compressed air rock drills was used for first time in

the world tunnel project (David chapman.2010). Moreover, various way and combinations of the

structure of tunnels were made for different purposes through out of the history. For example in

the USA highway tunnel was made for first time as the submerged tube steel circular shells and

opened in 1928. Also by year 1933 the biggest tunnel underwater was finished in the UK which

wide enough for four lanes of traffic (David chapman.2010).

Tunnels have not just used for traffic and food store, in primary stage of finding gold and jewels

underground, tunnels were also created in many deep excavations in mining fields in order to

preventing these mining fields from collapse by using tunnel support. At the start timber was used

as some types of support for protection of rock collapse during transporting minerals to surface

and gave secure safety place for workers. Figure () shows example of timber support

(Szechy.1966)

Figure () shows timber frame support for mining tunnels (Szech.1966)

In the twentieth century there has been huge growth of long networks of tunnels to provide the

needs in both of hydroelectric- power and water-supply systems. There has also been substantial

tunnelling activity in connection with the circulating-water systems of large generating stations

(Ponnuswamy and Johnson Victor 1996).

Furthermore, the raise in world population and the quick enlargement of cities required even more

needs and purposes for using tunnels for instance in drains, sewers, channel, water supply, cable

tunnels and other uses. The need for water led to ever bigger dams needing tunnels, sometimes

during construction for diversions, sometimes permanently. Moreover, in recent decades with the

growing of population the number of vehicles also increasing therefore it has became a common

phenomenon of daily traffic congestion, pollutes air and creates conflicts with the pedestrians. On

ground surface the traffic became a real deteriorate by extending more lanes in existing road

which most of time is unlikely to ease the traffic problem. Hence, the tunnelling for underground

metro and railway, road vehicles has assumed increased importance because of the need to expand

the transportation infrastructure in the country to cope with the anticipated magnitude of the

economic activities. Also major progress projects such as rapid travel schemes in metropolitan

cities, expressways connecting major cities, and also building tunnel as a subway has been used

successfully in the crowded cities of the world for pedestrians walking and safety.

The process of excavating a tunnel in ground is not simply a procedure of deciding where the

tunnel is to go. There are many concerns of general uncertainties and unknowns when dealing

with the underground structure. These variables can variety from small inconveniences to major

challenges to the designers and constructors of the tunnels. The uncertainties can be geology of

the area, ground water, initial drilling core which cover only 0.0005% of the actual excavation

volume of a tunnel in any project etc (Wahlstrom. 1973).

Today with advance of technology different types of tunnels have introduced which accelerate the

rate of excavating ground and more importantly methods standard uses to control workplace

hazards in underground construction as long as appropriate precautions are taken to protect

workers in a variety of situations. Furthermore, regulation standard such as Occupational Safety

and Health Administration (OSHA) relating to underground constructions have established during

1970s and improved over the years to add new defensive measures and enhance worker safety.

Training requirements for all workers involve in underground project must be taught to identify

and respond to risk related with this type of work (Ref:OSHA construction tunnelling Pdf).

There are many options available these days for the construction of tunnels. The selection of

which tunnelling technique to use must be made on the basis of the known and suspected ground

condition, in combination with other aspects such as access, possible local tunnelling traditions

and skills, as well as costs. Hence, in view of the fact this thesis intends to present a

comprehensive introduction to different types of tunnels and construction, impact of environment,

collecting previous experience and researches of tunnel and finally what will be future of the

tunnels.

In view of the fact that these modest beginnings there has been an explosion of tunnelling all over

the world and we can now almost certainly claim on a practical level to be able to construct

tunnels anywhere, through any ground.

1.2 different types of tunnelling

Following recent introduction it might be importance to detail the engineering basics of the

different types of tunneling. Tunneling has been using in many ways and many purposed

throughout of history. it can be better to classify as following:

1.3 Impact of Tunnels in Environment

1.4 Health and Safety and Risk management in Tunneling

Health and risk management in construction create unique challenges due to the nature of the

industry and these challenges are in more serious hazard when dealing with underground

structures. Normally those who works underground construction must be aware of high risk that

might be facing that can be include engineers, owner, designer and contractor of a project. The

UK code of practice for risk management of tunnel describes the “risk” as the mixture of the

outcome or severity of an exposure and its possibility of happening (Pennington.etc.2006).

Furthermore, a risk assessment in any type of project including tunnel and underground structure

is the organized and formalized method of recognizing and computing hazards in terms of cost,

duration of project, safety for employers and employees as well as the impact of surrounding area

and environment. There are many report and researches are related to civil engineering industries

underground and on ground are confirming that the construction industry as one of the most

dangerous field. In according to (Joyce.2001) report study of accidents over five years from 1981

in building and civil engineering (underground and on ground) showed that 739 people were died

in the construction industry. Also throughout the period from 1981 to 2000 figure () is illustrated

numbers of death for each year. So it can be seen that casualty is very constant and less

improvements for future. Therefore someone can get into conclusion behind such a connection

between construction activity levels and losses is that health and safety is still not a sufficient

enough to protect workers and reduce risk also priority to attract investment in training.

Figure () shows number of fatalities each year from 1981 to 2000 (Joyce.2001).

Furthermore, (Joyce.2001) was argued that the analysis of the main causes of accidents could be

prevented by the application of reasonable practicable precautions. Also is showed that a lack of

supervision by line managers in the construction industry and a lack of communication and

connection among the members of the professional level to lower level of works at the pre-

construction stage as well as introducing dangers and identify risks in industry toward workers.

Additionally, in tunnel constructions many hazards such as (unstable ground, water, noise, dust,

moving machinery and electricity) have the potential for harm to persons, the tunnel and the

surrounding environment. Over the past few years there have been a number of spectacular tunnel

collapses around the world which have resulted in both workers and members of the public being

killed. These risk of workplace can be different and directly related to choose type and method of

tunnel for instance the mechanized tunneling is found to be less risky because only those entering

the cutter-head for inspection and maintenance are facing dangers well on other hand when a

collapse does occur with a shield driven tunnel in an urban area, it might be greatest risk for

public and those on the surface (Chapman.2010).

1.3 methods of design and construction of tunnels

It is hard to simplify the use of a particular construction method in view of the fact that each

project is unique and has numerical of constraints and unpredictable condition that should be

considered when selecting a construction method.

Tunnel construction methods (cut and cover, shield driven, bored, drill and blast,

immersed tube, NATM)

Geometry shape (Circular, rectangular, horseshoe, oval/egg

Ground conditions (soft, subaqueous, mixed face, rock)

Lining and support system (unlined rock, cast in place concrete, shortcrete/gunite,

precast liners, steel/iron plate, masonry, slurry wall (Ref:best practices for roadway

tunnels design)

Now day methods of design and construction of tunnel has magnificently improved especially in

engineer and soil mechanic fields. Today the construction of tunnel in development countries has

to consider greater safety and much better working conditions than an historical counterpart. Also

with improvements in design and construction the diversity of use has been widened and tunnels

are not simply using for mines and shelters that they used to be. At present time the human race

excavates for transportation, mining, storage, deposition of waste and so on. In a very simple way

within according to (Walhstrom.1973) a tunnel can be described as a long narrow pathway,

essentially linear excavated underground opening which the length normally is greater than the

width and height.

Tunnels are different from other civil engineering structures, in buildings and any other

construction above ground such as bridges the using materials normally can be defined and

testable properties, whereas for tunnels this case is different. Table () below is shown some

problems associated with tunnel design and construction and comparison with above ground

construction projects (Ref: Tunnel construction by David Chapman, Nicole Metje and Alfred

Stark.2010).

Table () shows comparison between tunnels and structures above ground (Ref: Tunnel

construction by David Chapman, Nicole Metje and Alfred Stark.2010)

Construction material

Loads Safety

Structure above ground

Construction

Materials are tested during production process and

guaranteed by the quality control procedures

All loads and forces are affected a structure can be known by using structural

analysis method.

Safety factor can be determined base on known loads and

properties of the construction materials

Tunnel construction

Uncertainty of the ground properties and materials are incapability to influence its

properties

Loads can be only found by estimating therefore

analysis of loads is basically unidentified.

due to major of uncertainties related to the loads and material properties it is impossible to find

factor safety of the tunnel construction

due to some of the problems associated with tunnel design and construction for instance

supporting system which is made up of concrete and steel in any types of tunnel projects. can be

considered to be challenge in engineering field because it is a complicate mixture works of ground

and composite process which needs to understand of a soil condition in addition to structural

problems. Therefore plan of this dissertation is going to be covered various types of tunnels and

classification of soils as well as methods of design and construction as major parts of this study.

1. Cut and Cover Tunnels

The Cut and Cover methods are sophisticated engineering techniques for tunnel construction in

urban and interurban areas. Initially this method was industrial for unban passageway structures

where the slightest possible disruption of traffic is required thereafter the method has used in

highway, railway projects but appeared to be less favourable due to issues related to instability of

ground during construction (Mouratidis.2008).

Additionally the Cut and Cover tunnels methods of construction are normally shaped as a frame

box structure with a separating wall and walkways to each track giving an average box width of

10m and the depth of 10m to 12m is normally more economical and more practical then mined or

bored tunnelling (Federal Highway Administration (FHWA).2013). The technique is often

preferred for the construction of shallow tunnels and it is built inside an excavation and covered

over backfill material when construction of the structure is complete. In the soft ground areas a

temporary diaphragm walls or sheet piling might be used to protect sides from collapse (Nicholas

& Krishnan.2000). With regards to the impact environment it is fairly sensitive and even less

damaging because of backfilling the cutting area. Figure () shows construction procedures of the

cut and cover method (Mouratidis.2008).

Figure () shows stages of construction for the Cut and Cover techniques (Mouratidis.2008)

Furthermore, in according to (FHWA.2013) the cut and cover system needs support to prevent the ground from falling and blocking groundwater into excavated area therefore three common support categories can be used:

1) Open Cut slope : it is used where enough room is available to open cut the area of the

tunnel and slope the sides back to meet the adjacent existing ground line and is taking into account

the natural repose angle of the in-situ material and the global stability.

2) Temporary Support system : it is support vertical or almost vertical faces of the

digging in areas where sufficient room is not available. This type of support is not bearing loads of

the tunnel structure and it remains underground after being backfilled. Furthermore, mostly this

type of support can be classified as flexible or rigid such as sheet piling and soldier pile and

lagging walls.

3) Permanent support system: it is similar to the Temporary Support system however

this support becomes part of the tunnel to carry structure loads. From engineering point of view

this system is considered to be working as rigid systems which have more load carrying capacity

than flexible systems. Example of permanent support slurry walls, soldier pile or secant pile walls.

Figure () demonstrates an example of the cut and cover tunnel construction with both the

Temporary and the Permanent support wall systems.

Figure () shows temporary and permanent support wall systems (FHWA.2013)

Eventually there are issues need to be concern while using the Cut and Cover tunnel system

during design and construction. It is necessary to assess and mitigate of construction impacts on

adjacent structures. Also it is vital for engineers to be familiar with systematic features of analysis

soil movement as a result of the excavation (FHWA .2013). Last but not less the method also has

extensive surface disruption along the route during construction.

2. Immerse Tube Tunnels ( look at for extra work on

http://books.google.iq/books?

id=dUBaw8fQRAMC&pg=PA20&redir_esc=y#v=onepage&q&f=false)

An immersed tube tunnel is other types of tunnel systems. It is normally a best way of

constructing a tunnel across a water way. In according to (Lunniss and Baber.2011) the history of

immersed tunnel initially is going back to early 1800s where the first concepts developed in

England and by 1893 the first immersed tunnel was built. Before first immersed tunnel was

successfully built many proposed and attempted were made, for instance within according to

(Ingerslev.2010) Edward Reed in 1882 proposed a submerged railway tunnel across the English

Channel to connect England and French but due to French fear invasion the parliament of

England did not accept the propose.

Immersed tube tunnels are constructs differently from other type of tunnel system. It is ideals for

crossing rivers and mostly using pre-fabricated elements which are assemble in the dry place near

the tunnel location. These parts are floated into the river/sea bed and joined together. It is very

important to ensure adequate stability for these parts against uplifting (Davie Chapman.2010).

Additionally, in the world there are two types of immersed tube tunnel which are:

2.1 Steel Shell

The steel shell type is conventionally chosen in the United States. It is normally built as single or

double shell construction see figure (). It is consisted of relatively thin-walled composite steel and

concrete rings. The steel shell provides the water barrier and uses for the water tightness.

Figure () shows example of single and double for steel shell immersed tube tunnel

(Chapman.2010)

2.2 Concrete

Concrete is other material used for immersed tube tunnel. Normally double and multiple tubes

with rectangular shape can be made. Traditional casting method is carried out by using movable

steel shutter as formwork. At first the base slab is constructed and then the vertical bearing walls

casts to be ready for last part which is roof slab to complete the rectangular box (Chapman.2010).

Furthermore, traditional cracking in concrete is a major problem facing immersed tube tunnel due

to heat of hydration generated from different stages of concrete casting. In order to solve cracking

problems either carry on casting of the full cross section or cooling pipes to control temperature

and construction joints between the walls and top and bottom slabs can be used (Chapman.2010).

Figure () shows some examples of the rectangular concrete immersed tube tunnel.

Figure () shows examples of rectangular concrete immersed tube tunnel (Chapman.2010)

Additionally, for construct typical immersed tube tunnels some general stages need to be taken

in any immersed tube tunnels which are as following:

a) Tunnel parts with a complete cross section and required length are manufactured in a large

ship or on a port later transport for tunnel position.

b) In order to prevent water, these cross section element parts are closed by temporary

bulkheads.

c) To make the elements sunk, some temporary water is putting into the ballast tanks inside

the elements, then the elements are joined together and form watertight connection.

d) At the initial stage of construction the tunnel foundation has to be prepared.

e) To prevent the tunnel from damage backfilling the excavation and placing rock protection

on the top are used.

f) Finally the tunnel is sealed and pumped out the water inside.

Demonstrate the sequence of these stages is clearly shown in figure () in more details.

Figure () shows typical sequence for the construction of an immersed tube tunnel (Chapman.2010)

Around world other types of immersed tube tunnels have constructed in different approaches and

are not discussed in scope of this project for example, steel sandwich composite, concrete

monolithic but figure () is displayed recent trends in structural form of immersed tube tunnels.

Figure () shows trends in structural form of immersed tube tunnels (Lunniss and Baber.2011)

and

Within according to (Lunniss and Baber.2011) after the first transpiration tunnel was built in

1910, growth in immersed tunnels worldwide has been dramatic increased especially in United

States, Europe and significantly in Asia and far East. It can be assumed that in average of around

one project opening per year. Figure () is shown rate of immersed tunnel construction worldwide

for transportation tunnels.

Figure () is shown rate of immersed tunnel construction worldwide for transportation tunnels

(Lunniss and Baber.2011)

Additionally, further improvement techniques in constructing immersed tunnels have led contries

such as the United States, the Netherlands and Japan are became the majority of building

immersed tunnel and more recently the People’s Republic of China, including Hong Kong has

shown dramatic increased in the rate of immersed tunnels constructions because of the geological

lying regions with major cities and rivers. Figure () shows the number of immersed tunnels built

by country include those under construction (Lunniss and Baber.2011).

Figure () numbers of the immersed tunnels built by country (Lunniss and Baber.2011).

Eventually, it can be seen that the immersed tube tunnels around world has became more

interesting and rapidly built especially in those countries which economical development are

significantly increases and improvement of technology and techniques of building this type of

tunnel is hel of econ

3. Drill and Basting tunnel method

Aim:

Objectives:

The objective of this study is shows the history of tunnelling and understanding of design and

constructing as well as the problems pose on in modern construction and major uncertainties that might

be happened during construction.

Contents:

Methodology, resources

Project title

Abstract

List of figure

List of tables

Symbols and notation

Formula

Synopsis

Chapter One (Background and History of different types of TunnelsTunnels are mostly can be defined an underground structure, which considers to railway tracks, passageway. Tunnels are built either above sea level or likely in modern day technology builds

under sea-level. The worldwide development in progress of civil engineering infrastructure over the past years has led to a major enhance in the numbers and types of tunnels constructed for road, railways and water supply.

History of Tunnelling

Tunnelling dates back to centuries in human kind developments. Many data and researches are published different times of building tunnels therefore there is not exact known date of construction first tunnel.

Impact of Tunnels in Environmental and Health and Safety Issues

In construcation of any type of structures there is always need to considered environment affacts risk of health and safety issues. Everything around us are called environment therefore almost most of activities are going on somehow effect and have impact in environment. The study of this chapter is going to include aim and objective of these bullet points:

Introduction into history of tunnelling in the past to the present time.

Background of information , collection of previous knowledge about that

subject

Background of this project, familiar knowledge about the area of research

History of the construct tunnelling and related aspects.

Explain various types of soils and dealing with them during construction.

Consider hazards and health and safety of constructing tunnels.

Chapter Two

Literature review.

Past experiences and fundamental aspects of use.

Methods of design and construction of tunnels.

Literature ReviewIn the previous chapter tunnel were described as underground passage that constructed for the

various reasons. Then this chapter is going to discuss researches and many studies were made

about different types of tunnels, as well as methods and technique of fundamental aspects of

construction and select appropriate methods.

Classification of tunnels can be contented of many types such as railway tunnels, metro system,

highway, sewage tunnels etc. All these types of tunnels have unique way to deal with,

constructing and design of tunnels can be directly related to geological location and condition of

ground as well as sectional shapes which are usually determined by their purpose of use.

Moreover, the most fundamental operations of tunnelling need to carry out survey and soil

condition carefully, also considering using appropriate mechanism and machines to excavation of

ground and immediate support of ground. Most importantly managing of water during

construction and finally using right permanent support to hold ground and prevent the tunnel of

collapse and failure.

Nowadays there is a continuous and growing required for constructing tunnels for various reasons.

Methods of making tunnels are always in progress due to high demand and well developed

technology.

In the mining industry drill and blast has been used rapidly for excavate of ground however, the

mechanical excavators is replaced with helps of new technology and therefore it has achieved

lower costs and faster development schedules as well as sufficient mine planning and detailed

performance analysis. Also using mechanical excavators can make perfect estimation of

production rates and costs.(Application of tunnel boring machines.M.Cigla)

Method of construction:

Look at “tunnel file”

Tunnel types

History of Tunnel-Boring Machine (TBM)In the history of tunnel the earliest record of a working Tunnel Boring Machine (TBM) is going

back to 1856 under different name called “Wilson’s Patented Stone-Cutting Machine” named by

Charles Wilson (Ref:Practical Tunnel Construction, by Hemphill.2013). Wilson were develop his

idea and improved his machine see figure () in 1857 and the machine was used to build the 7645 m

tunnel in western Massachusetts. The tunnel in western Massachusetts was required to be 0.33 m

wide and outer diameter of 7.3 m and penetration rates were estimated to be (0.254−0.61)m per

hour. Unfortunately the Wilson Improved machine was not continued due to high cost of used and

commercial failure (Practical Tunnel Construction, by Gary B. Hemphill).

Figure () shows Wilson’s Improved Machine in 1857 (Hemphill.2013)

Tunnel Boring Machine (TBM):Tunnel Boring Machine (TBM) is one of very essential methods in modern day technology and it

has become a preferred way of construction tunnels nowadays. The TBM is designed to carry out

a circular cross section. It is used to drilling and excavating tunnels through all different types of

soil and rock layers. In addition, the TBM is well accepted in environment and it is considered to

be less harming to underground and disturbance to land. (Engineering Survey system

TBM.Andrew file). Tunnels in soft soil are often constructed as bored tunnels therefore the TBM

is chosen to be better choice compares to cut and cover tunnel techniques. To some extent the

TBM is less expensive and different from the traditional drill and blast method. Moreover, tunnels

by the TBM are used both in urban and non-urban areas in soft and in a sub-aqueous environment.

(refreec singh pdf).

In general overall advantages of using TBM can be demonstrated as following:

Fast rate of advance in producing a round, smooth and un-shattered bores.

Over break is less in ground during excavation than other methods.

During excavation ground is not weakened hence support is less required.

Reducing risk of collapse of the excavation face.

It is economical especially in the long tunnel length.

Nevertheless there are some disadvantage points of using the TBM which can be verified as

following:

In term of using in short tunnels, it is expensive.

It can be used only for circular tunnels cross section.

Construction of TBM is considerably costly.

In most of cases the TBM machine components can be different from each other so Figure () is

shown an example of the TBM machine with main components and functionalities of them.

Figure () shows a typical layout of TBM

1. Cutter Disc: it is at the front end of the machine and is responsibility to excavate rock or

soft ground by the rotating mechanism which is made the teeth cutting rock under pressure

of wheels.

2. Shield Skin: it is responsible to prevent the soil from getting inside the machine and give

clear space for the workers.

3. Pushing Jack: it is located on top side of the machine straight behind the Cutter disc, it is

work by hydraulic and pushing the Cutter forward during operation.

4. Main Drive: Drive is work by electricity and provides a force to rotate the Cutter disc.

5. Screw Conveyor: it is worked to get out the broken parts of soils at the Cutter disc and

feed onto a conveyor system.

6. Erector: to erect the segments to form a complete ring after shoving at the tail of the TBM.

7. Back up Facilities: it is a channel to travel with the TBM and to service the operation.

Because of demonstrated abilities in achieving high rates of advance in civil tunnel construction

the TBM machine is always shown a major interest in the hard rock mining industry initially for

development of doorway, as well as ventilation, haulage and production drifts. Furthermore, in

order to achieve lower costs and faster development schedules the choice of using mechanical

excavation method with sufficient planning and detailed performance analysis is better than using

Drill and Blast method (Ref:Application of tunnel boring Secured). Mechanical excavation offers

several advantages over drill and blast for all types of tunnel excavation some of these

comparisons are shown in table () (Ref:Application of tunnel boring Secured).

Mechanical excavation Drill and Blast excavation

Safety of workers is in great improvement

during operation of the machine.

High risk for workers due to exclusion of

blasting and toxic smoke

Reducing ground disturbance which

considerably lower support requirements for

stability opening

Mass ground disturbance due to blast and

needs sufficient support for stabilisation of

opening

During excavation smooth walls created by

machine boring which helps to induce

ventilation requirements

It is necessary to build smooth walls and

installs ventilation.

However, despite the comparisons above there are several issues were rose by looking back to

history of TBM in mine industry. In according to (Ref:Application of tunnel boring Secured)

TBMs have been used in mining operations from time to time the earliest application dates back to

late of 50’s and following decades. The capability of the TBMs machine was shown high rates

achievement in many projects during those decades. However, overall costs were not be justified

due to lack of experience of the workers applying these type of machines for excavate which

caused very low machine utilization rates. Also these machines were not originally designed for

mining fields. In addition lack of accurate estimation and unexpected ground conditions, such as

very weak and broken ground or fault zones made these machines unfavourable for using in mine

fields.

In most recent years, application of the TBMs in mining operations have came back to point of

interest, the TBM is improved successfully due to experiences gained with helps of technology in

cutter design and machine components systems also awareness of the manufacturers to design

appropriate and more specific machine for mining excavations. (Ref:Application of tunnel boring

Secured)

Within according to (Ref:Application of tunnel boring Secured) reliability of the TBM in most of

tunnelling projects is directly related to many factors influencing the TBM performance during

excavations. These factors can be concise as following:

1. Intact Rock Properties The intact rock property is commonly related to measure of Uniaxial Compressive Strength (UCS)

of rock property (Ref:Application of tunnel boring Secured). Normally during excavation it is

necessary to know how much force needs to break a rock, in order to evaluate the resistance of the

rock against the indentation of the cutting tool the UCS is carried out to measure and great

awareness is needed to work out how the sample of the rock can be fail during UCS testing. Some

times during UCS test two types of failures can be observed, which are structural and non-

structural failures. Structural failure is fail along existing rock defects, such as joints, fractures,

bedding or foliation of the rocks. However, where the testing of the samples is not crashed due to

any defects and happened in an “intact” manner the sample is noted as having failed in a non-

structural behavior. Widely speaking the non-structural failure is of essential because it cannot be

predicted. Figure () is demonstrate the UCS samples of the rock which are compressed and tested

under hydraulic machine for structural and non-structural failures.

Figure (), left hand side non-structural failure, right hand side structural failure (Rock Mechanics)

2. Rock Mass Properties In the excavation process different layers of the rocks are existed on the ground therefore foliation

and bedding are significantly related to fracture propagation between cuts of the rocks and directly

related to the direction of the machine advance cutter disc. Furthermore, intact rock properties

together with rock mass characteristics should be well investigated for selection of proper tunnel

boring machine (TBM). Also within according to (Factors influencing performance of hard.) the

Norwegian University of Science and Technology (NTNU) has developed a hard rock TBM

prognosis model that shown it is important to evaluate the orientation of foliation planes with

respect to the angle of Alpa (α) that is the angle measured between the plane of weakness and

tunnel axis. If the angle of the machine advances parallel to across foliation planes of the rocks it

will reduce machine penetration because of increased difficulty of rock breakage (Ref:Application

of tunnel boring Secured). Figure () is demonstrate cutting direction parallel to foliation.

Figure () illustrates cutting direction parallel to foliation (Ref:Application of tunnel boring

Secured)

However, it is on the most favorable boreability when the foliation is perpendicular to direction of

machine advance. This case generally helps the cracks initiation and growth between adjacent cuts

figure () represents this type of excavation.( Ref:Application of tunnel boring Secured)

Figure () illustrates cutting direction perpendicular to foliation

Moreover, in order to find out the best way to measure high performs of machine it is necessary to

test the tensile strength of the rock in various directions. For instance figure () is shows sample of

loading direction with respect to foliation/bedding planes in order to represent the crack

propagation across or along the weakness planes.

Figure () loading direction for tensile testing (Ref)

3. Machine type and Specifications

Generally type of TBM machine can be considered to be other factors of the excavation that is

consequence the sufficiently and fasting the process. The component of the machine such as thrust

and power are the key to providing adequate amount of forces and torque to support the

excavation of operation. Enough force to efficiently penetrate the tools into the rock surface.

( Ref:Application of tunnel boring Secured)

4. Cutter Geometry Front of the TBM machine is end by several cutting tools which are provided for the transmission

to break rocks and excavate ground. These cutting tools are worked by energy which is generated

by the machine. Within according to (Ref:Application of tunnel boring Secured) a single disc

cutters are the most regularly used roller cutters for hard rock tunnel boring machine because they

are the most competent types of rolling cutters since the entire capacity of the bearing is

concentrated into a single narrow edge.see an example of the single Disc Cutters in the figure ()

below.

Figure () shows Single Disc Cutters

5. Cutting Geometry The Cutting Geometry is considered to be one of the most crucial factors in performance of the

TBM. In order to make cutting works efficiency it is necessary to manage and calculate

approximately spacing and the depth of the cutter into the rock per cutter-head. Furthermore, the

spacing of cutters has a magnificent impact on the chipping mechanism and effectiveness of

boring. Extensive past research and data resources analysis have studied that optimal cutting

efficiency is directly related to the ratio of spacing to penetration of the cutting access.

Furthermore, the interaction between adjacent cuts in maximum when a spacing for a given cutter

penetration optimum. In order to achieve high result of excavation manufacturers need to use the

ratio of spacing to penetration 10 to 20 for tougher rocks and hard/brittle rock respectively. Figure

() shows effect of spacing over penetration ratio on cutting efficiency. (Ref:Application of tunnel

boring Secured)

Figure () shows spacing over penetration ratio on cutting efficiency

Overall, there are many other factors which are effects the performance of the TBM during

excavation process. Also there are several special issues that have to be identified and dealt with

when working with TBM in any kinds of excavation so that project economics and completion

schedules can be assessed more accurately.

Chapter three, Types and purpose of TunnelsIn this chapter types and purpose of tunnels can be widely explained

Storage and deposition of waste tunnels

Passageway and Traffic tunnels

Rail and transportation tunnels

Military and defence tunnels

Chapter Four, Design and Construction of Tunnels In this chapter a short list of many uncertainties that need to be concerned during design and construction is going to be discussed as following:

Uncertainty when dealing with any underground project

Uncertainty due to the geology of the area that will determine the feasibility

and the cost of the undertaking.

Uncertainty due to ground water table which is the most complicate

parameter to calculate.

Chapter Five, outcome & Discussion

Chapter Six, Conclusion

Chapter Seven, Reference

Reference

Lunniss, R. and Baber, J. 2011. Immersed tunnels. London: Taylor & Francis.

Ponnuswamy, S. and Johnson Victor, D. (1996) 'Transportation Tunnels'

Szechy, K. 1966. The Art of Tunneling. Akademiai Kiado, Budapest, Hungary. Use of

shotcrete for underground Structural Support.

Zhao, J., Shirlaw, J. N. and Krishan, R. 2000. Tunnels and underground structures.

Rotterdam: Balkema.

Appendix

Bibliography

http://www.citethisforme.com

https://www.fhwa.dot.gov/bridge/tunnel/pubs/nhi09010/

index.cfm

https://www.fhwa.dot.gov/bridge/tunnel/pubs/nhi09010/index.cfm

https://www.fhwa.dot.gov/bridge/tunnel/pubs/nhi09010/index.cfm

http://www.citethisforme.com/

my plan for dissertation last tunnel

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