• PURPOSES OF TUNNELLING

• EFFECTS OF TUNNELLING ON THE GROUND

• LINING OF TUNNELS

• ECONOMICAL ASPECTS OF TUNNELLING

• GEOLOGICAL CONSIDERATION FOR SUCCESSFUL TUNNELLING

• OVERBREAK

• EXAMPLES OF TUNNELS OF INTEREST AND IMPORTANCE

INTRODUCTION

INTRODUCTION

Tunnels are key elements of the nation’s infrastructure. Mostly invisible

and out of sight, they play a key role in urban transportation, water and

sewerage transportation, and in hydro electric power and many other

sectors.

The seminar will cover an introduction to all forms of tunneling in a

coherent and systematic approach. Particular emphasis will be placed

on the attendees understanding both the full range of tunneling

techniques available and their applicability in various soils and physical

constraints. The seminar will also emphasize understanding and

mitigating the inevitable risks involved in tunneling.

PURPOSES OF TUNNELLING

from avalanches of snow or falling rock.

A Tunnel is an underground passage. In general, tunnels are at least twice as long

as they are wide and are completely enclosed on all sides, save for the openings at

each end.

A tunnel may be used by pedestrians, cyclists, motor vehicles, or rail traffic. A tunnel

may also be used for a canal or a flow of water—for consumption, for hydroelectric

purposes, or for sewers— or it may carry other utility services such

as telecommunication cables or steam pipes. Some tunnels are designed as wildlife

crossings.

Overbridges:An overbridge can sometimes be built by covering a road, river, or railway with brick or still arches, then leveling the surface with earth. In railway parlance, a surface-level track that has been built or covered over is called a covered way.

Protection for railways: A snow shed is a kind of tunnel built to protect a railway from avalanches of snow or falling rock.

• Utility ducts: Utility ducts are man-made tunnels created to carry two

or more utility lines underground. Through co-location of different utilities

in one tunnel, governments and companies are able to reduce the costs

of building and maintaining utilities.

o Types Of Tunnels

EFFECTS OF TUNNELLING IN THE

GROUND

The "tunnel effect", when talking about long stretches of road, refers to the

environment surrounding the driver that begins to merge towards the central

point of the horizon. This effect can be noted at high speeds, when driving

on straight smooth roads. The effect is amplified if the environment

surrounding is monotonous. The "tunnelling effect" can cause nausea,

confusion to drivers as well as letting fatigue settle in at a higher rate, making it one major cause in sleep related accidents.

Tunnel lining waterproofingVarious types of waterproofing materials are used in modern

tunnel construction. Solid waterproofing is made of

waterproof building organic or synthetic film filter materials,

synthetic resinous materials, and steel sheets.

Cat-in-place tunnel lining, placed in stable rock ground,

protect from water by means of external waterproof installed

before lining construction. After that reinforced framework is performed.

Economical aspects of Tunneling

Tunnels have been essential feature of Railways particularly forcrossing hills and high altitude areas.. An attempt has been made to bring out some relevantimportant aspects of Tunneling.

Following factors are to be kept in mind in conception of alignment:

following factors are to be kept in mind in conception of alignment:

i. Cost aspectExecution costRunning cost – Has bearing on decisions of grade and curve

radius

ii. Time of execution conceptInterest cost, Delayed benefit / goodwill cost

iii. Method of executionDrill and blast method

• Prevalent method in capital rich countries, generallyrequire uniform stratification

Sedimentary rocks

Mostly, these rocks are formed under relatively uniform conditions over relativelylarge areas. Subsequent metamorphism, folding and faulting, even though relativelycomplex, do not change the sedimentary rock to the extent that its originalcomposition and areal extent cannot be recognised.

Intrusive igneous rocksThese are less predictable than extrusive igneous rocks and the accuracy of projectionis of the same order as their areal extent. Hence a dyke can be interpreted betweendata points and projected to depth to the approximate extent of its surface expression.The least reliable feature of an intrusive igneous rock mass is the contact of a crosscuttingintrusive body.

Examining the cut kerf

of the Robbins

waterjet-assisted

hard-rock TBM in granite

Overbreak of rock beyond the desgined periphery of a tunnel is a structural risk

which more than occasionally results in filing of a claim by the contractor. It is

difficult to estimate the overbreak risk at the time of tender with sufficient degree of

accuracy because of the uncertainty associated with the geology, construction

technique, and the interaction of these two domains.

The key variables that influence the extent of overbreak, and their interactions, are

illustrated through the proposed interaction matrix.

The assessment of overbreak for a tunnel excavated using the conventional, drill-

and-blast technique, is performed using an approach that integrates simulation

and sensitivity analysis.

OVER BREAK

Pir Panjal Railway Tunnel

The Pir Panjal Railway

Tunnel or Banihal railway

tunnel is an 11.215 km (7

mile) railway tunnel

located in Pir Panjal

Range of

middle Himalayas in Jam

mu and Kashmir, India, north of Banihal town.

Progress of the project :

The new 11.215 km (7 mile) long Banihal-Qazigund tunnel for the Kashmir

Railway line connecting Bichleri Valley of Banihal with Qazigund area of Kashmir

Valley has been constructed as a part of its Udhampur-Srinagar-Baramulla rail link

project. The boring was completed in four years in October 2011, its lining and laying

of rail tracks was completed in the next one year and trial run commenced on 28

December 2012. The tunnel was commissioned on 26 June 2013 and commercial

runs started from 27 June 2013.

The rail tunnel reduces the distance between Quazigund and Banihal by 17 km

(from 35 km by road to 17.5 km by train).[4]

Banihal railway station is situated at 1,702 m (5,584 ft) above mean sea level. The

railway network in Kashmir from Banihal toBaramulla is now 137 km. Until the

148 km Katra-Banihal section of Kashmir railway gets constructed in another five

years in 2018, people can travel from Jammu Tawi or Udhampur to Banihal by road

and take the train from Banihal to Srinagar through the Banihal railway tunnel.