Training Report_khasa Kothi

8/2/2019 Training Report_khasa Kothi

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JAIPUR DEVELOPMENT AUTHORITY

TRAINING REPORT

ON

KHASA KOTHI FLYOVER

Submitted by:


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JDA at a Glance

Strengthening Faith: Jaipur Development Authority

Jaipur Development Authority (JDA) has been committed to workingfor the benefit of the citizens of Jaipur with planned implementation

of development schemes and is consistently striving to take Jaipur at

higher levels of progress. Jaipur is one of the most well-planned

cities of its times and planned development has always been central

to its ideology.

Jaipur Development Authority came into existence by the

Government of Rajasthan with a vision to combat and manoeuvre

the growing requirements of a large city in wake of the increasing

population and to help give Jaipur a planned look compatible and

comparable to any metropolitan city of repute. JDA was authorised

powers and a green signal to speed up the development and

progressive growth of the entire city to rapidly change the face of

Jaipur. To meet these important needs JDA sprang into action and

started to understand the necessary needs of the city.

According to the requisites, JDA has been working towards time-bound construction, creation and development of the western part of

Jaipur based on major scientific and hi-tech strategies. Thus, Jaipur

has been beautified intensively to augment the tourist attraction in

the city and to raise the living standards to suit convenience of its

citizens.

The major undertaking of JDA includes the following:

* Infrastructural development of Jaipur region by construction of

flyovers, bridges, parking places.

* Development of commercial projects and residential schemes,

etc.

* Development of basic amenities like community centres, parks,

ring roads.

* Development and rehabilitation of kacchi bastis etc.


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* Preparation and implementation of master plan.

* Preparation and implementation of guidelines for colonisation.

* Environmental development by planning and implementing

roadside plantations and by developing eco-friendly schemes.

* Development of rural area around Jaipur.

* Development of transport facilities like Mass Rapid

* Transport System (MRTS), Transport Nagar, and major sector

roads.

According to the promises and commitments of the Rajasthan

Government, JDA has been time and again proving itself as a pioneer

of development, creating a state-of-the-art city of substance. JDA

has been working on widening all main roads, construction of over

bridges, under bridges and flyovers to regulate the traffic on roads,

minimize pollution, and ensure public convenience and safety. JDA

firmly believes in bridging the gap and reaching out to its citizens

and to provide them with quick and hassle-free service.

JDA...where town planning is a tradition.


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Contents

1. Introduction

2. Components of flyover

i) Foundation

ii) Piers and abutments

iii) Deck

iv) Pre-stressed concrete

v) Backfill and Reinforced earth wall

3. Test reports


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KHASA KOTHI FLYOVER

INTRODUCTION

The Khasa Kothi flyover is being constructed at one of the busiest

traffic junction in jaipur city. The flyover is being constructed on the

road connecting the railway station to Sindhi Camp bus stand to

facilitate the easy movement of traffic plying from station to Chandpole, M.I. road & Banipark area. The cost of project is Rs. 22.0 Crore

and length of fly over 740.0 Mts.

The work was commenced after the stone laying on 30.10.06. The

work was stopped due to order passed by Honble high court on

8.2.07 for maintaining status quo. This order was declared non

operative by Honble high court on 30.05.07 and work restarted

thereafter.

The work worth Rs. 6.50 Crore has been done by 20th April 2009. The

super structure work is in progress and 80% of reinforced earth wall

panel has been casted. The work is proposed to be completed by

August 2009.

Salient Features

Project Cost : Rs. 2200.00 Lacs

Agency : M/s Harish Chandra (I) Ltd.

Consultant : Span Consultant Pvt Ltd.,

Delhi

Work order amount : Rs.19,63,69,312.00

Stipulated date of commencement : 15.04.2006


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Stipulated date of completion : 14.10.2007

Work Period : 18 Months

Date of Start : 30.10.2006

Physical Features

Total Length : 740 Mts.

Total Width : 16.75 Mts.

Width of Roads : 2 X 7.5 Mts. (2 lanes each)

Median Width : 1.00 Mts.

Via Duct Length : 455 Mts.

Approaches : 285 Mts.

Nos. of Spans : 14

Service Roads : 5.5 Mts. On either side

The grade of concrete used in the construction is M-50.


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SOME IMPORTANT THINGS!!!

1) Always wear a good quality helmet on the

site.

2) Always wear shoes on the site.

3) Wear safety belts if required.

4) Safety nets should be provided wherever it is

necessary.


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MAJOR COMPONENTS OF FLYOVER

FOUNDATION

Since the bridge has to carry a big live load and its dead weight is

also very large so we cannot go for simple foundation but pile

foundation.

Pile foundation is one type of deep foundation. It is used where the

good soil is at higher depth (10 or 15m) or soil having low bearing

capacity. Pile is also used for tall structures. In pile foundation the

load coming from the super structure is taken by pile cap and

equally distributed in no of piles, pile transfers this load into the soil.

The Khasa Kothi flyover consists of 115 bored cast in situ piles with

14 pile caps.

The diameter of each pile is 1200 mm with depth 25 meters and

different piers have different set of group of piles.

Pile group under A1,P2,P3,P11,P12 and A2


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Pile group under P1,P4,P10 and P13 Pile group under

P8

Pile group under P5,P6 and P9 Pile group under P7

A1 and A2 are Abutment 1 and 2; P1,P2,P3.. are Pier no 1,2,3..

The depth of pile cap is 2 m which is 500 mm below ground level.


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INSTALLATION PROCEDURE OF PILES

Step 1 --- Excavation of Pile Shaft

The bored pile equipment set including hydraulic oscillator, hydraulic

vibrator, hammer grab and rock chisel used in this project is very

common and being widely used for shaft excavation.

a. Set out the correct position of the bored pile on site.

b. Excavate about 3 - 4m of the pile to remove shallow

obstructions and then backfill, wherever necessary.

c. Install the bottom section of temporary casing of required

diameter into the ground by oscillating and jacking or byvibrating motion exerted by the oscillator and the vibrator

respectively.

d. Set up hydraulic oscillator or vibrator in conjunction with a

crawler crane.

e. Excavate within the casing by hammer grab and redrive the

steel casing simultaneously by using the heavy duty casing

oscillator / vibrator. Rock chisel in various types will beemployed for removal of obstruction or hard materials during

the above process.

f. Extend the steel casing by bolting or welding on additional

casing during the excavation.

g. Water will be pumped into the casing during excavation and

constant water head will be maintained so as to prevent any

ingress of material from the bottom of casing.

h. Verticality of the casing will be monitored by means of spirit

level from time to time.

i. Continue the above procedure until the founding level of pile

has been reached .

j. Pile base enlargement will be formed by employing a bellout

chisel or a reverse-circulation drill as indicated in the workingdrawings.


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Step 2 --- Cleaning of Pile Shaft

Final cleaning will be carried out by the air-fitting method using high

pressure air compressors. The slime and muddy water within the

casing will be cleared and delivered into a desilting tank before

discharge.

Step 3 --- Tremie Concreting

a. The pile shaft will be concreted by "Underwater Tremie

Technique". The tremie pipe sections will be inserted and be

jointed until it reaches the bottom of pile shaft. Concrete will be

poured into the tremie pipe by using a concrete skip.

Concreting will be carried out in one continuous operation until

the required level has been reached.

b. As concreting proceeds, the level of the concrete relative to theground level will be monitored by measuring with weighted

tape after each skip of concrete is placed.

c. The base of the tremie pipe will be kept with a minimum depth

of approximate 1 to 2m below the surface of the concrete.

d. The temporary casing will be extracted simultaneously by the

oscillator in the course of concreting. A head is always

maintained between the top of concrete and the bottom ofsteel casing.


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Step 4 --- Installation of Reinforcement

After the completion of concreting, dowel bars of required length

and numbers will be installed into the pile shaft and down to the

predetermined level before the extraction of bottom steel casing.

PIERS & ABUTMENTS

The Khasa Kothi flyover has 15 piers including two abutments.

The maximum height of the pier is about 6 m.
http://www.cse.polyu.edu.hk/~ctpile/insta/i-bpile/i-tc1.jpg


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A typical Expansion joint used in bridge

DECK

The Khasa Kothi bridge is of box girder type bridge which is

comprised of prestressed concrete. The box is typically of

trapezoidal in cross-section. Compared to I-beam girders , box

girders have a number of key advantages and disadvantages.

Box girders offer better resistance to torsion, which isparticularly of benefit as the bridge deck is curved in plan.


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Additionally, larger girders can be constructed, because thepresence of two webs allows wider and hence stronger flanges

to be used. This in turn allows longer spans.

On the other hand, box girders are more expensive to fabricate,and they are more difficult to maintain, because of the need for

access to a confined space inside the box.

The span length is of range of 25 m to 50 m.

The box girders are made of concrete and were casted in place

using falsework supports. First 75 m span is of solid type deck and

then it consists of box girders i.e. from A1 to P3 and P11 to A2 the

deck is solid with the depth 1.2 m.

The depth of box girder is different as per load requirement. From P3

to P6 and P9 to P11 it is 2.2 m and from P6 to P9 it is 2.5 m.

The slope of the deck is 1 in 29 m. The total width of the deck is

16.75 m including 1m wide median and two crash barrier of width

0.375 m.


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Reinforcement pattern for box girder.

Pre-stressed Concrete

The technique of pre-stressing eliminates cracking of concrete under

all stages of loading and enables the entire section to take part in


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resisting moments. As dead load moments are neutralized and the

shear stresses are reduced, the sections required are much smaller

than in reinforced concrete.

Prestressing can be accomplished in three ways: pre-tensionedconcrete, and bonded or unbonded post-tensioned concrete.

Pre-tensioned concrete

Pre-tensioned concrete is cast around already tensioned tendons.

This method produces a good bond between the tendon and

concrete, which both protects the tendon from corrosion and allows

for direct transfer of tension. The cured concrete adheres and bonds

to the bars and when the tension is released it is transferred to theconcrete as compression by static friction. However, it requires stout

anchoring points between which the tendon is to be stretched and

the tendons are usually in a straight line. Thus, most pretensioned

concrete elements are prefabricated in a factory and must be

transported to the construction site, which limits their size. Pre-

tensioned elements may be balcony elements, lintels, floor slabs,

beams or foundation piles.

Bonded post-tensioned concrete

Bonded post-tensioned concrete is the descriptive term for a method

of applying compression after pouring concrete and the curing

process (in situ). The concrete is cast around plastic, steel or

aluminium curved duct, to follow the area where otherwise tension

would occur in the concrete element. A set of tendons are fished

through the duct and the concrete is poured. Once the concrete has

hardened, the tendons are tensioned by hydraulic jacks that reactagainst the concrete member itself. When the tendons have

stretched sufficiently, according to the design specifications (see

Hooke's law), they are wedged in position and maintain tension after

the jacks are removed, transferring pressure to the concrete. The

duct is then grouted to protect the tendons from corrosion. This

method is commonly used to create monolithic slabs for house

construction in locations where expansive soils (such as adobe clay)

create problems for the typical perimeter foundation. All stresses


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from seasonal expansion and contraction of the underlying soil are

taken into the entire tensioned slab, which supports the building

without significant flexure. Post-tensioning is also used in the

construction of various bridges; both after concrete is cured after

support by falsework and by the assembly of prefabricated sections,

as in the segmental bridge.

The advantages of this system over unbonded post-tensioning are:

1. Large reduction in traditional reinforcement requirements as

tendons cannot destress in accidents.

2. Tendons can be easily 'weaved' allowing a more efficient

design approach.

3. Higher ultimate strength due to bond generated between the

strand and concrete.

4. No long term issues with maintaining the integrity of the

anchor/dead end.

Unbonded post-tensioned concrete

Unbonded post-tensioned concrete differs from bonded post-

tensioning by providing each individual cable permanent freedom of

movement relative to the concrete. To achieve this, each individual

tendon is coated with grease (generally lithium based) and covered

by a plastic sheathing formed in an extrusion process. The transfer

of tension to the concrete is achieved by the steel cable acting

against steel anchors embedded in the perimeter of the slab. Themain disadvantage over bonded post-tensioning is the fact

that a cable can destress itself and burst out of the slab if

damaged (such as during repair on the slab).


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The advantages of this system over bonded post-tensioning are:

1. The ability to individually adjust cables based on poor field

conditions (For example: shifting a group of 4 cables around an

opening by placing 2 to either side).

2. The procedure of post-stress grouting is eliminated.

3. The ability to de-stress the tendons before attempting repair

work.

In Khasa Khothi flyover the method used for pre-stressing is

unbonded post tensioning system. In this system first of all high

tensile steel cables/wires (also known as strands or tendons)

encased in sheathing pipes were laid as per design and then

concreting is done. After the hardening of concrete the stretching of

wires was done by means of hydraulic jacks. The jacking was done

from both ends. The wires were jacked a few percent above their

specified initial pre-stress in order to minimize creep in steel and toreduce frictional loss of pre-stress.

The wires are anchored to concrete after stretching by wedge action

producing a friction grip on wires.


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Cables left for stressing before concrete is poured

We can see that the cables are in a grouped in every pipe. In the

above picture there are 19 cables in one group.


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Sheathing pipes carrying cables.

We can see in above picture that the cables are curved as per

design requirement.


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Stretching of cables by hydraulic jack after hardening of concrete

The jack used in above picture has the capacity to stretch 4 cables

at a time. This jack can perform both operations i.e. stretching of

wire as well as tightening of wedges.


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Calibrated pressure gauge to read directly the amount of tension

applied

It is however the practice to measure the elongation of steel so that

the magnitude of pre-stress can be calculated independently and

checked against the gauge reading.


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Covering of cables after grouting

The cables are covered by concrete to prevent corrosion. The

grouting is done through the hole as seen in above picture (in red

circle) and then the hole is then bolted as shown (in blue circle).


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PROBLEMS LIKELY TO CAUSE DURING OR AFTER CONCRETING

1. Segregation : Segregation of concrete can be defined as

separation of coarse aggregate from mortar, resulting in their

non-uniform distribution. Improper mix proportion resulting in

large proportion of coarse particles as compared to small

proportion of fine particles caused the separation of coarse

particles from mortar. Segregation is also caused by incorrect

handling of mixed concrete during transportation and

placement, and also by over-compaction.

2. Honeycombing : The separation of coarse aggregate frommortar leaves voids in coarse aggregate unfilled and this

phenomenon is called honeycombing. Honeycombing causes

decrease in the density of concrete and hence reduction in the

strength of the concrete.

3. Bleeding : Bleeding is a form of segregation in which water in a

concrete mix rises to the surface during placing it. It is because

more water is present than is necessary for the cement pasteto lubricate the aggregate particles and the solid constituents

of the mix are able to hold all the mixing water when they

settle down. Thus the water rises up and appears on the

surface of the compacted concrete. Sometimes, finer particles

such as cement are also carried with the rising water. The

water trapped by the superimposed concrete results in a

porous weak and the non-durable concrete. If the rising water is

trapped on the underside of reinforcement, then a zone of poorbond is created. This water form voids on evaporation and

makes the concrete weaker.

PRECAUTION TO BE TAKEN DURING PLACING OF CONCRETE:

1. Under no circumstances, the water should be added to the

concrete during its passage from mixer to the formwork


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2. The formwork or the surface which is to receive the fresh

concrete should be properly cleaned prepared and well-

watered.

3. As far as possible, the concrete should be placed in singlethickness. In case of deep sections, the concrete should be

place in successive horizontal layers and proper care should be

taken to develop enough bonds between successive layers.

4. The concrete should be thoroughly worked around the

reinforcement and tapped in such a way that no honeycombed

surface appears on removal of the formwork.

5. The concrete should be place on the formwork as soon as

possible.

6. During placing, it should be seen that all edges and corners of

concrete surface remain unbroken, sharp and straight in line.

7. The placing of concrete should be carried out uninterrupted

between predetermined construction joints.

CONSOLIDATION OF CONCRETE:

The main aim of consolidation of concrete is to eliminate air bubbles

and thus to give maximum density to the concrete.

In Khasa Kothi flyover the Internal or Immersion vibrators are used

for consolidation of concrete. These vibrators consist of a steel tubewhich is inserted in fresh concrete. This steel tube is called the poker

and it is connected to an electric motor. The poker vibrates while it

is being inserted. The internal vibrators should be inserted and

withdrawn slowly and they should be operated continuously while

they are being withdrawn. Otherwise holes will be formed inside the

concrete.


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BACKFILL AND REINFORCED EARTH WALL

Reinforced earth is a composite material formed by the friction

between the earth and the reinforcement. By means of friction the

soil transfers to the reinforcement the forces built up in the earth

mass. The reinforcement thus develops tension and the earth

behaves as if it has cohesion. Reinforced members are composed of

thin wide strips also called as ties.

For reinforcement the GI strips are used which are 40 mm wide and

5 mm thick and the length varies as according to the tensile stresses

at various place and levels.

The facing elements for backfill are precast concrete panels having

dimension 1.5m x 1.5m with some aesthetic appearance.

The dry density of the compacted soil was kept 1.85 to 1.9 gm/cc

and the moisture content was kept at 8 to 9%.

Procedure

Place and compact initial lifts of select Granular backfill up to bottom

row of panel tie strips. The level of the compacted backfill should be

50mm above the tie strips. In order to avoid pushing the brace

panels out of alignment, initial lifts of backfill are neither placed nor

compacted against the back of the panels. Compact each backfill lift

using a large smooth-drum vibratory roller except within a 100 cm


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zone directly behind the panels where a small hand-operated

vibratory compactor must be used to avoid undue panel movement.

After compaction has taken place, check wall alignment visually and

with a level adjust panels as necessary.

A drainage system is made near panels by laying 20mm coarse

aggregates near panels up to a width of 60 cm throughout the depth

and at the bottom a semi perforated pipe is used to drain out the

water.

Immediate gradation and moisture testing is required if either

excessive panel movement or backfill pumping occurs during

construction.

Compaction: Large smooth-drum vibratory rollers are used to

accomplish mass compaction of backfill materials, except for fine

sands.

Sheep foot rollers are never to be used for compaction of backfill.

Fine uniform sands, which contain more than 60 percent passing a425 sieve used for backfill, must be compacted using a smooth

drum static roller.

Vibratory compaction equipment should not be used to compact fine

uniform sands.

Moisture content of backfill material during placement should be

approximately 1% to 2% more than its optimum moisture content.

Reinforcing Strips:-

Place reinforcing strips on the compacted backfill. Position strips

perpendicular to the facing panels, unless otherwise shown on the

plans. Reinforcing strips are supplied in lengths as shown on plans.

Connect each reinforcing strip to the embedded panel tie strip by

inserting the end of the reinforcing strip into the gap between the

two exposed ends of the tie strip. Match the three holes and push a


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bolt through the holes from below, threading on a nut and

tightening.

Dump backfill onto the reinforcing strips so that the toe of the

backfill pile is 3-4 ft from the panels. Spread the backfill by pushingthe pile parallel to the panels.

Metal tracks of earthmoving equipment must never come in contact

with the reinforcing strips. Rubber-tired vehicles, however, can

operate directly on the exposed strips if backfill conditions permit

and care is exercised.

At the joints of panels a special type of semi permeable textile

known as geo-textile is used to stop the backfill from slipping out ofthe panels.


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Spreading of backfill

In the above picture we can see the arrangement of panels. No

binding material is used to join the panels they are interlocked with

each other.


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GRADATION FOR COARSE AGGREGATE

TYPE OF AGGREGATE 20mm Date:- 30-05-09

TOTAL WEIGHT TAKEN 2922 Gms

SieveSize

WeightRetained

%Retained

%Cumulative

Retained

%Passing Remarks

25 0 0.00 0.00 100.0020 172 5.89 5.89 94.1110 2662 91.10 96.99 3.01

4.75 68 2.33 99.32 0.68Pan 20

TYPE OF AGGREGATE 10mm Date:- 30-05-09


SieveSize

WeightRetained

%Retained

%Cumulative

Retained

%Passing Remarks

12.5 0 0.00 0.00 100.0010 268 9.06 9.06 90.94

4.75 2514 85.02 94.08 5.922.36 120 4.06 98.14 1.86Pan 55

SieveSize

For 20 mm For 20 mm

Combined

Grading

As per IS 383

%Passing

%Passing

%Passing

%Passing

Lower

LimitUpperLimit

20 100% 63% 100% 37%10 94.11 59.29 100 37.00 96.29 95 100

4.75 3.01 1.90 90.94 33.65 35.54 25 55Pan 0.68 0.43 5.92 2.19 2.62 0 10


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GRADATION FOR COARSE AGGREGATE

TYPE OF AGGREGATE SAND Date:- 30-05-09


Sieve

Size

Weight

Retained

%

Retained

%Cumulati

veRetained

%Passin

g

Remark

s

Zone II

4.75 12 2.26 2.26 97.74 90-100

2.36 28 5.27 7.53 92.47 75-100

1.18 65 12.24 19.77 80.23 55-90

0.6 190 35.78 55.56 44.44 35-59

0.3 157 29.57 85.12 14.88 8-30

0.15 69 12.99 98.12 1.88 0-10

PAN 10

AS PER IS 383 SAND IS IN ZONE II


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