A Tunnel is an Underground Passage Through a Mountain

7/31/2019 A Tunnel is an Underground Passage Through a Mountain

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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 areconstructed purely for carrying water (for consumption, hydroelectric purposes or as sewers); others carry services such astelecommunications 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 tube is a kind of underwater tunnel composed of segments, constructed elsewhere and floated to the tunnelsite to be sunk into place and then linked together. They are commonly used for road and rail crossings of rivers, estuariesand sea channels/ harbours. Immersed tubes are often used in conjunction with other forms of tunnel at their end, such asa cut and cover or 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

Date 18/04/2012

Cut-and-cover:Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over with anoverhead 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.
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/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/Trenchhttp://en.wikipedia.org/wiki/Cut_and_coverhttp://en.wikipedia.org/wiki/Tunnel


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1) Quality Controla) Gas Controlb) Dust Control

2) Quantity Controla) Ventilation

b) Auxiliary or face ventilationc) Local exhaust

3) Temperature-Humidity Controla) Coolingb) Heatingc) Dehumidification

NATURAL VENTILATIONNatural ventilation is the term used to describe airflow resulting from a pressure difference caused by naturalmeans. 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 thro ugh fans & du cti ng. If a fan whil e working on a mine is exhaustingair there from, the fan is then, due to centrifugal force , c rea ting a par ti al vacuu m a t it s c ent 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 shou ld run dependsaltogether on its construction. While some fans may stand a rim speed of 16,000 ft. per minute, others will not standmore 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 passthrough the mine, and hence the ventilating current is maintained as long as the fan runs. When the fan is running thepressure of the air is always less at the inlet of the fan than outside, and the differencebe tween th i s p re s su re and the p re s su re o f the a tmosphe re i s the p re s su re p roduc ing ven t i l a t ion , o rthe ext ent to whi ch a v acuum is app roa che d by the fan . M any differently constructed fans are being used forthe purpose of ventilating mines

Material handling:

Hoisting system (vertical shaft) Haulage system


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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=8d 2 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:

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

HOISTING SYSTEM

MATEIRAL HANDLING

SKIP

1.SINGLE DRUM

2.DOUBLE DRUM

3. FRICTION(KEOPE)

PERSONALS CAGES


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Problem: Calculate the daily production of a shaft equipped with a balanced friction hoisting system, giventhe 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 relationshipsbetween 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-aqueoustunnels.

A sinking cycle consists of the following unit operations:1. Drilling2. Blasting3 Mucking and Hoisting4. Support or shaft lining5. Auxiliary operations:a) Dewateringb) Ventilationc) Lighting or illuminationd) Shaft centering


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HOISTING: It is used for hoisting/lowering of men, material and muck. Two practices are prevalent i.e. by installing the permanent hoistand its attachments; else with the use of a temporary hoist, head-gear and other attachments. This hoisting system usuallyhandles a load up to 150 200 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 supportscould range from 6m to 40 m. Once this length is covered by the temporary lining and before advancing further, thepermanent 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 isa common used. The steel tubing is used in conjunction with freezing method of sinking.

AUXILIARY OPERATIONS: Dewatering

During 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 dirtywater.

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 readilyraised 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 aresuspended at the side of the shaft. Ventilation duct range terminates at least 6 m above the shaft bottom to avoid its damagedue to blasting. The whole shaft acts as return.

Illumination:Proper illumination is necessary at shaft bottom.Pneumatically operated light, consisting of a cluster of 4 6 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 ischecked from time to time, by the use of a centering device. Plumb bob for vertical shaft and Brinton compass or theodolitefor incline shafts to check the centering.

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 unstablesuch as sand, mud, gravel or alluvium, or when excessive amount of water is encountered, which cannot be dealt with thesinking pumps. Also when in some situations, both sets of these conditions are encountered. Also when in some situations,both sets of these conditions are encounteredSpecial method: Piling system Caisson methods Cementation Freezing method Shaft drilling & Boring.


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PILING SYSTEM:This method is suitable only for sinking through the loose ground near the surface.Wooden piles 2 5 m long, 50 70 mm thick & 150 200 mm wide, or steel piles are used. Steel piles are stronger than that of wood. Wooden piles are shod with iron at bottom so as to pierce the ground. The piles are driven down by heavy mallets, andare placed edge to edge so as to form a complete circular lining After putting the first set of piles, another set of piles is thendriven 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 groundsufficient 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 isbuilt. The space between this lining and the piles is filled with some packing material.

CAISSON METHOD:This method is popularly known as Drop-Shaft and is common in civil engineering works while one has to sink through theriverbed. This method is suitable to sink through the running ground to a depth somewhat greater than the one, which can benegotiated by adopting the pilling method.

CEMENTATION: In this special method of shaft sinking the liquid cement is injected through boreholes into the gullet stratain order to fill up any cracks, cavities, fissures and pores. The cement, in turn, strengthen the strata and ultimately make themimpervious 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 to10,000 g.p.m capacity failed but this method could succeed. The cement is injected at a pressure of 80 4000 psi. Followingsteps are followed:1. Boring/Drilling2. 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 mostdifficult ground conditions. The process consists of formation of a cylinder of frozen ground, in the center of which it ispossible 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 shaftto be sunk. In these holes through steel tubes brine solution is circulated. The brine solution, which absorbs the heat from theboreholes, progressively, causes the ground to freeze, and form the ice wall of sufficient thickness. This artificially createdwall of ice prevents the inflow of water into the shaft being sunk. There are four distinct steps that are followed in thissystem, and these are: Drilling and lining of boreholes Formation and maintenance of the ice column Actual sinking operations, and thawing of ice-wall.

SHAFT DRILLING AND BORING:There are two methods: Drilling and Boring ; which without aid of explosives can undertake shaft sinking operation. Sinkingis most hazardous work amongst all mining operations, and that too, while driving through the aqueous, cavable and softground. Drilling method gives advantage of sinking shaft without the entry of the crew into it during its drivage. Thus, themethod is safe and proves economical in the conditions where the conventional methods may not prove viable.


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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 bedriven, must be first treated or consolidated. Secondly, the problem of removal of the large volume of cuttings, which withouta 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

Problems: IN adit to be drawn into granite such that the dominations joints, is strike roughly perpendicularto the adit axis in depth at 35degree against the drive direction. The of the adit is 3m wide which isunsupported and the following data is gathered from the site.


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RQD = 70 %Strength of rock=150MpaJoint spacing= .5mConditions are joint is likely rough surface separation less then 1mm. hard joint wall rock and the ground water is undermoderate pressure. Find the standard time of the of the adit using rock mass rating. Condition is unfavorable.

Solution:

Given value from tableRQD=70% 13STRENGTH OF ROCK=150Mpa 12Joint spacing= 0.5m 20Rough surface separation less then 1mm= 20Ground water is under moderate pressure= dipping= 04

Add these data

13+12+20+20+04=69

For adit the condition is unfavorable =-10So 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 a geomechanical classification system for rocks , developed by Z. T. Bieniawskibetween 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 discontinuities5. 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 fromfield surveys. The sum of the six parameters is the "RMR value", which lies between 0 and 100.

The classification table for the RMR system

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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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RMR Rock quality

0 - 20 Very poor

21 - 40 Poor

41 - 60 Fair

61 - 80 Good

81 - 100 Very good

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

J n (joint set number) J r (joint roughness number) J a (joint alteration number) J w (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.

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

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A Tunnel is an Underground Passage Through a Mountain