Class Work of Tunnel Engineering

7/31/2019 Class Work of Tunnel Engineering

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Balochistan University of Information Technology, Engineering and

Management Sciences Quetta

BUITEMS Quality & Excellence in EducationQuality & Excellence

Submitted by: Nouman Rahim Khattak

Class: Bs (Mining Engg) 8th

Semester

Cms ID: 5714

Assignments: Class Work

Subject: Tunnel Engineering

Submitted to: Engr, Sir Abdul Sami G Abro

Due Date: 28 June 2012

Department Of Mining Engineering

Takatu Campus Airport Road, Baleli, Quetta

www.buitms.edu.pk

*


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Tunnel

A tunnel is an underground passage through a mountain, beneath a city or under a waterway.

It may be for pedestrians and/or cyclists, general road traffic, motor vehicles, rail traffic, or for a canal. Some tunnels are

constructed purely for carrying water (for consumption, hydroelectric purposes or as sewers); others carry services such as

telecommunications cables.

Types of tunnel:

Water tunnel Rail tunnel Road tunnel Cable tunnel Ventilation tunnel Storage tunnel

Cut and cover tunnel Cast-insitu tunnel in a water Imeresed tunnel Borad tunnel

An immersed tubeis a kind of underwatertunnelcomposed of segments, constructed elsewhere and floated to the tunnel

site to be sunk into place and then linked together. They are commonly used for road and rail crossings of rivers, estuaries

and sea channels/ harbours. Immersed tubes are often used in conjunction with other forms of tunnel at their end, such as

acut and coveror bored tunnel, which is usually necessary to continue the tunnel from near the water's edge to the entrance

(portal) at the land surface.

Ground stress: initial stress+ virgin stress

Virgin Stress: initial stress

Induced stress: Lateral stress

General formula:

For vertical stress v=depth/40Mpa

For horizontal stress H/ V=3-DEPTH/500 MPA

Example: A tunnel is excavated at the depth of 400m .find the vertical and horizontal stress in the regions?

Solution:

For vertical stress v=depth/40Mpa

v= 400/40=10Mpa

For horizontal stress H/ V=3-DEPTH/500 MPA

h=3-400/500

h=-7.94Mpa
http://en.wikipedia.org/wiki/Tunnelhttp://en.wikipedia.org/wiki/Tunnelhttp://en.wikipedia.org/wiki/Tunnelhttp://en.wikipedia.org/wiki/Cut_and_coverhttp://en.wikipedia.org/wiki/Cut_and_coverhttp://en.wikipedia.org/wiki/Cut_and_coverhttp://en.wikipedia.org/wiki/Cut_and_coverhttp://en.wikipedia.org/wiki/Tunnel


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Date 18/04/2012

Cut-and-cover:

Cut-and-cover is a simple method of construction for shallow tunnels where atrenchis excavated androofedover with an

overhead support system strong enough to carry the load of what is to be built above the tunnel.

Types of roof fall: by (vier) 1970

Dust Roof Fall: when pyrite is occurred in shale in the immediate roof stratum then shale clubles and fall in the formof dust. Thickness of roof fall is less from 1ft.

Lenticular Roof Fall: When soft shale is occurring in between two sand stone rolls in immediate roof, then shall fallsin soft shale the excavation.

Concentration fall: When iron stone concentration is occurring in the formation of black shale in the immediate roof,which falls down after the excavation made.

Slate roof fall: In this fall black shale in the immediate roof rocks breaks in large slabs. Slabs means a large piece ofstones and slate means flat plates.

PYRITE: By oxidation and Hydration it is formed. it is a types of iron ore, it is 30% costly to recover it. During thisprocess Mg also formed. Pyrite also found in coal

BLACK SHALE: It is not a coal. The percentage of Carbon is greater in it.

SLATE: is a type of sedimentary rock. Black shale is found in it.

Floor Heaving:

It causes due to high horizontal stress occurs when pillar strata is stronger then floor.

Floor Buckling:

Floor rising in the slabs forms, due to horizontal stress, occurs when floor stratum is competent.

Bearing:

The angle between two points on the horizontal plane. It is measured as 45degree EAST NORTH, NORTH EAST etc.
http://en.wikipedia.org/wiki/Trenchhttp://en.wikipedia.org/wiki/Trenchhttp://en.wikipedia.org/wiki/Trenchhttp://en.wikipedia.org/wiki/Roofhttp://en.wikipedia.org/wiki/Roofhttp://en.wikipedia.org/wiki/Roofhttp://en.wikipedia.org/wiki/Roofhttp://en.wikipedia.org/wiki/Trench


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24/04/2012

GEOLOGICAL STRUCTURE OR GEOLOGY OF SITE:

THE topics are:

Bore holes: Data collection, formation, faults, and folds. Joints, structures observing and then these data put in the software

Inclined Strata: in inclined beds, when a tunnel is driven parallel o the strike direction, there is a tendency of therocks to fall into the tunnel from the side where the beds dip into the tunnel. This is the particularly the case, if the

hard and soft rock beds. Like sandstone and shale are present.

Across the strike: when a tunnel is made across the strike of rocks, it will traverse beds of different rocks. In suchcase there will be downward pressure from the roof. Water troubles are likely tube encountered whenever porous

beds ore found.

25/02/2012

TUNNELS IN FOLDS:

FOLDED ROCK: in tunnel that are driven through the joint blocks from inverted keystones in the arch and cave rockfalls. In case the rocks happen tube water bearing the water into the tunnel and cases great difficulties

In a tunnel that cuts through anticlines, the danger from sudden rock falls is less because the joint block will be in the shape

of normal keystones and hence they are unlike to fall into the tunnel. If the water bearing strata are met with, in water

troubles will be less because in anticlines the water flows away from it.

AFTER MID TERM

Shaft sinking:

Excavation of shaft in mine to minerals is called shaft sinking. In other words it is also called Adit.

Types of shafts: Vertical shaft Inclined shaft Horizontal shaft Staple shaft (blind shaft)

Shapes of shafts:Circular shaft: it is used in water bearing strata brick lining, Ring usage, Sustain high stress, easy to distribute the

surrounding stresses of rocks.

Square shaft and rectangular shaft are used in Dry formation. Having less stresses and usage of low costly timber.


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Shaft sinking methods:

Freezing and thawing Pilling system(for lose material like sand) The drop shaft or casing system ( concrete rings) Rings system Short creating (concrete)

DATE 16/05/2012

Ventilation system:

Natural system Artificial system

>>>>Purpose of ventilation is to supply fresh air to workers to dilute or disperse harmful gases to acceptable

level to cool the deeper mines Mine ventilation is mainly related to the quantity control of air, its movement and

its distribution.

>>>>Conditioning functions and processes commonly used in mines consist of the following:

1) Quality Control

a) Gas Control

b) Dust Control

2) Quantity Control

a) Ventilation

b) Auxiliary or face ventilationc) Local exhaust

3) Temperature-Humidity Control

a) Cooling

b) Heating

c) Dehumidification

NATURAL VENTILATIONNatural ventilation is the term used to describe airflow resulting from a pressure difference caused by natural

means. This pressure difference is due to difference between air densities in intake and return shafts. Source of

unequal densities is difference in elevation and temperature in the intake and the return shafts.

Only temperature difference is not enough to produce N.V.

Artificial system

The fresh air is s uppl ied and cont roll ed through fans & ducting. If a fan whil e working on a mine is exhausting

air there from, the fan is then, due to centrifugal force , c rea ting a par tial vacuum at it s cent er or axi s; the ext ent of

th is vacuum depends on the peripheral or rim speed of the fan. The peripheral speed at which a fan should run dependsaltogether on its construction. While some fans may stand a rim speed of 16,000 ft. per minute, others will not stand

more than 5000ft. per minute. When the inlet of the fan is connected to the mine the only air that can get to the fan must pass

through the mine, and hence the ventilating current is maintained as long as the fan runs. When the fan is running the

pressure of the air is always less at the inlet of the fan than outside, and the difference


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betweenth is pressure and the pressure of the a tmosphere is the pressure producing vent i la t ion , or

the ext ent to whi ch a vacuum is app roache d by the fan . M any differently constructed fans are being used for

the purpose of ventilating mines

Material handling:

Hoisting system (vertical shaft) Haulage system

DATE 17/05/2012

Wire ropes

Carbon .5% Silicon .11% Manganese 0.48% Sulphur b0.033% Phosphate 0.14%

Weight of wire rope= for a single drum W=8d2 y lbs

D= dia of wire in inches Y=length of wire in yards

TESTING OF WIRE

Tension Test Torsion test Bending test Wrapping test Hand testing

Cares of ropes:

HOISTING SYSTEM

MATEIRAL HANDLING

SKIP

1.SINGLE DRUM

2.DOUBLE DRUM

3. FRICTION(KEOPE)

PERSONALS CAGES


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Causes of deterioration Storage of ropes Handling of ropes Care in daily use if 1/3 of upper side is broken

Problem: Calculate the daily production of a shaft equipped with a balanced friction hoisting system, given

the following data,

Shaft/day=3 Shat time= 7.2hr Skip capacity= 12tons Cycle time 1 trip=85sec/skip

Solution:

85sec/60sec=1.4min for 12ton 60min/1.4min=42.85*12tons=514.2ton/hr 514.2tons*7.2hr=3702.85ton/shaft 3702.85*3=11,108.5 ton in 3 shaft Total daily production=11,108.5tons

DATE 22/05/2012

Stereographic projection: Stereographic projection is a graphical technique for representing the angular relationships

between planes and directions on a 2D piece of paper.

Pole: in stereographic projection the pole is a reference point from where we measure the angle.

Application: Can be used to calculate angles between planes

28/05/2012

Shaft sinking:

Shafts are required for the following purposes:8

mining the mineral deposits

Temporary storage and treatment of sewage

Bridge and other deep foundations

Hydraulic lift pits

Wells

in conjunction with tunneling system or network for the purpose of lifts, escalators, Stair and ladder-ways, ventilation,

conveyance of liquid, carrying pipes and cable in river crossings, drainage and pumping particularly from sub-aqueous

tunnels.


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A sinking cycle consists of the following unit operations:1. Drilling

2. Blasting

3 Mucking and Hoisting

4. Support or shaft lining

5. Auxiliary operations:

a) Dewatering

b) Ventilation

c) Lighting or illuminationd) Shaft centering

DRILLING:

Use of sinkers to drill holes of 3238 mm. diameter and the shaft jumbos (equipped with number of drifters, (fig. 14.5) todrill holes of 4055 mm. dia. is made. The holes length varies between 1.5 m and 3 m if the sinkers are used, and it can beup to 5 m in case of the shaft jumbos. Wedge cut, pyramid cut (figs 14.4 (a), (b), (c)) and step cut (fig. 14.4(d)) are the

common drilling patterns adopted. Wedge cut is more popular in the rectangular shafts whereas pyramid cut in the circular

ones (fig. 14.5)). Step cut is adopted if the make of water is high and shaft is of a large cross-section, so that the face can be

divided into two portions to allow a continuous dewatering. Number of holes in a pattern is a function of hole diameter, shaftdiameter and type of strata. The following formulae11 for determining the number of holes, if drilling is with a shaft jumbo

having hole dia. in the range of 4555 mm could be used:

BLASTING: In practice shaft bottoms during sinking are usually full of water; therefore, use of high-density water resistant

explosives, such as nitro-glycerin based, is made to charge the holes. Use of water or sand-clay mixture can be made to act as

a stemming material. Usually series-parallel connections are made to connect the detonators at the face and this circuit is then

connected to the blasting cable suspended in the shaft and leading right up to the surface. Face is blasted after taking due

precautions. The latest development, as claimed by the Nitro-Nobel9 is the use of emulsion explosive with booster and Nonel

detonators.

Advantages:

Less expensive than cartridge explosives Faster loading than cartridge explosives Provides full borehole coupling Reduce drilling as holes required are of large diameter than those for cartridges Better fragmentation.

In dry strata different other explosives are used.

If electric blasting pattern is not used than the safety fuse should be as long to firer can reach to surface at the time of firing.

LASHING AND MUCKING:


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Lashing: It is the arrangement that is made for the loading of blasted muck into conveyance for its disposal. Presence of

water, limited space and the time required to install mucking equipment makes this operation a time consuming activity. It

occupies about 5060% time of a sinking cycle. Several types of shaft muckers are available The mucking efficiency depends

upon the size of rock fragments, hoisting depth, shaft cross-section and water inflow rate. The units are matched with 0.56m3

grabs in shafts of 68 m diameters; larger units and 0.85m3 grabs are used in the large shafts. Crawler mounted rocker

shovels have been used in very large shallow depth shafts and in small shafts down to 5.5 m dia. Small 0.28m3 remote

mounted grabs have likewise been employed. In very small shafts hand lashing is sometimes considered but this is costly,

rare and very unpopular now a days and it is more usual to set the minimum shaft size, which will facilitate the mechanical

cleaning system for reasons of efficiency and economy.

HOISTING:

It is used for hoisting/lowering of men, material and muck. Two practices are prevalent i.e. by installing the permanent hoist

and its attachments; else with the use of a temporary hoist, head-gear and other attachments. This hoisting system usually

handles a load up to 150200 tons.

SUPPORT OR SHAFT LINING:

Basically there are two types of lining: Temporary and Permanent. In some situations temporary support is not required,

whereas in others, it becomes essential to protect the crew and equipment from any side fall. Length of temporary supports

could range from 6m to 40 m. Once this length is covered by the temporary lining and before advancing further, the

permanent lining is installed. Before installing the permanent lining if feasible, Permanent lining can be that of bricks,

concrete blocks, monolithic concrete shotcrete and cast iron tubing.

The bricks and concrete block were earlier used in the dry and shallow depth. Monolithic concreting of the desired strength is

a common used. The steel tubing is used in conjunction with freezing method of sinking.

AUXILIARY OPERATIONS:

DewateringDuring sinking once the shaft has reached to the water table or beyond it, make of Water is unavoidable. Even before, inflowof water is usual. Dewatering is an important operation in shaft sinking.

Face pumps:are used if the of water is limited, this can be hoisted through the kibbles or water barrels. To fill thesebarrels pneumatically operated membrane face pumps are most suitable, as they can deal with muddy, silted and dirty

water.

Sinking pumps: If the water is beyond the handling capacity of the face pumps, then hanging pumps which can besuspended in the shaft together with the electric cables, motor, suction and delivery ranges, are used. it can be readily

raised or lowered..

Provision for the intermediate sump and pumps: When the shaft depth increases and make of water is sufficient, itis always preferred, as per Boky2 to have intermediate pump chambers with sumps at an interval not exceeding 250m. Keeping a standby pumping set is a normal practice during shaft sinking, as any moment an abnormal quantity of

water inflow can be expected.

VentilationFresh air, by a forcing fan installed at the surface is provided at the face through the rigid and flexible ducts, which are

suspended at the side of the shaft. Ventilation duct range terminates at least 6 m above the shaft bottom to avoid its damage

due to blasting. The whole shaft acts as return.

Illumination:Proper illumination is necessary at shaft bottom.

Pneumatically operated light, consisting of a cluster of 46 bulbs fixed at bottom.Luxi meter is used to measure the light quantity.

Shaft centering:Using the reference points, which are fixed before commencing the sinking operation to fix the shaft center? Centering is

checked from time to time, by the use of a centering device. Plumb bob for vertical shaft and Brinton compass or theodolite

for incline shafts to check the centering.


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SPECIAL METHODS OF SHAFT SINKING:it becomes necessary to adopt a special method/technique, if the ground through which shaft is to be sunk is loose or unstable

such as sand, mud, gravel or alluvium, or when excessive amount of water is encountered, which cannot be dealt with the

sinking pumps. Also when in some situations, both sets of these conditions are encountered. Also when in some situations,

both sets of these conditions are encountered

Special method:

Piling system

Caisson methods

Cementation

Freezing method

Shaft drilling & Boring.

PILING SYSTEM:Wooden piles 25 m long, 5070 mm thick & 150200 mm wide, or steel piles are used. Steel piles are stronger than that ofwood. Wooden piles are shod with iron at bottom so as to pierce the ground. The piles are driven down by heavy mallets, and

are placed edge to edge so as to form a complete circular lining After putting the first set of piles, another set of piles is then

driven but before this the ground enclosed is dug out, to the extent that the first set of piles is about 0.6 m in the ground

sufficient extra ground all around the proposed site of the shaft need to be dug and piled.

Once the firm ground is encountered, the permanent lining which could be either that of bricks, steel tubing or concrete is

built. The space between this lining and the piles is filled with some packing material.

CAISSON METHOD:This method is suitable only for sinking through the loose ground near the surface.

This method is popularly known as Drop-Shaft and is common in civil engineering works while one has to sink through the

riverbed. This method is suitable to sink through the running ground to a depth somewhat greater than the one, which can be

negotiated by adopting the pilling method.

CEMENTATION: In this special method of shaft sinking the liquid cement is injected through boreholes into the gullet strata

in order to fill up any cracks, cavities, fissures and pores. The cement, in turn, strengthen the strata and ultimately make them

impervious to water.

Thus, this method is applicable if the ground is firm but fissured. It is not suitable for running sand type ground conditions.

The success of the method lies due to the fact that, at many locations, in the heavy water bearing areas the pumps up to

10,000 g.p.m capacity failed but this method could succeed. The cement is injected at a pressure of 804000 psi. Followingsteps are followed:

1. Boring/Drilling

2. Cementation3. Sinking and walling.

THE FREEZING PROCESS:This method is suitable for any kind of heavily watered strata including quick sand. It has proved its success even in most

difficult ground conditions. The process consists of formation of a cylinder of frozen ground, in the center of which it is

possible to sink a shaft, by following the ordinary method of sinking.

The freezing is accomplished by boring/drilling a ring of holes slightly out side, around the site selected, for the actual shaft

to be sunk. In these holes through steel tubes brine solution is circulated. The brine solution, which absorbs the heat from the

boreholes, progressively, causes the ground to freeze, and form the ice wall of sufficient thickness. This artificially created

wall of ice prevents the inflow of water into the shaft being sunk. There are four distinct steps that are followed in this

system, and these are:

Drilling and lining of boreholes Formation and maintenance of the ice column

Actual sinking operations, and thawing of ice-wall.


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SHAFT DRILLING AND BORING:There are two methods:Drilling and Boring; which without aid of explosives can undertake shaft sinking operation. Sinking

is most hazardous work amongst all mining operations, and that too, while driving through the aqueous, cavable and soft

ground. Drilling method gives advantage of sinking shaft without the entry of the crew into it during its drivage. Thus, the

method is safe and proves economical in the conditions where the conventional methods may not prove viable.

SHAFT BORING:

Although the concept of shaft boring with the use of shaft borers (SBM), like tunnel borers (TBM) to drive horizontally,

came during sixties but it could not gain much popularity due to the fact that a difficult ground through which it needs to be

driven, must be first treated or consolidated. Secondly, the problem of removal of the large volume of cuttings, which without

a pilot hole leading to the lower accessing level, is a tedious task. The crew with the equipment has to travel on board.


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RQD:

A measure of rock mass integrity based on the condition of core samples


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Problems: IN adit to be drawn into granite such that the dominations joints, is strike roughly perpendicular

to the adit axis in depth at 35degree against the drive direction. The of the adit is 3m wide which is

unsupported and the following data is gathered from the site.RQD = 70 %

Strength of rock=150Mpa

Joint spacing= .5m

Conditions are joint is likely rough surface separation less then 1mm. hard joint wall rock and the ground water is under

moderate pressure. Find the standard time of the of the adit using rock mass rating. Condition is unfavorable.

Solution:

Given value from table

RQD=70% 13

STRENGTH OF ROCK=150Mpa 12

Joint spacing= 0.5m 20Rough surface separation less then 1mm= 20

Ground water is under moderate pressure= dipping= 04

Add these data

13+12+20+20+04=69

For adit the condition is unfavorable =-10

So 69-10=59

RMC is in class three,, it will be stable for 2 months without support.

DATE 11/06/2012

ROCK MASS RATING:The rock mass rating (RMR) system is ageomechanicalclassification system forrocks, developed by Z. T. Bieniawski

between 1972 and 1973.

The following six parameters are used to classify a rock mass using the RMR system

1. Uniaxial compressive strength of rock material2. Rock quality designation(RQD)3. Spacing of discontinuities4. Condition of discontinuities
http://en.wikipedia.org/wiki/Geomechanicshttp://en.wikipedia.org/wiki/Geomechanicshttp://en.wikipedia.org/wiki/Geomechanicshttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Core_recovery_parameters#Rock_quality_designationhttp://en.wikipedia.org/wiki/Core_recovery_parameters#Rock_quality_designationhttp://en.wikipedia.org/wiki/Core_recovery_parameters#Rock_quality_designationhttp://en.wikipedia.org/wiki/Rock_(geology)http://en.wikipedia.org/wiki/Geomechanics


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5. Groundwater conditions6. Orientation of discontinuities

Each of the six parameters is assigned a value corresponding to the characteristics of the rock. These values are derived from

field surveys. The sum of the six parameters is the "RMR value", which lies between 0 and 100.

The classification table for the RMR system

RMR Rock quality

0 - 20 Very poor

21 - 40 Poor

41 - 60 Fair

61 - 80 Good

81 - 100 Very good

Q-system

It is proposed on the basis of large number of cases studied/histories of underground excavation (in Norway).

Jn (joint set number)

Jr(joint roughness number)

Ja

(joint alteration number)

Jw (joint water parameter)

SRF (stress reduction factor)

Note:

It is a quantitative classification system.

Used for designing of tunnel support

It is use six different parameters to assess the rock mass quality.

Numerical range of Q ranges b/w 0.001.


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Problem:

Solution:

=90/4*0.5/3*2/1.3

=22.5*.166*1.53

=5.7

For graph:

Span or height in m/ESR or SRF=3/1.3

=2.30

Class Work of Tunnel Engineering

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