JAIPUR DEVELOPMENT AUTHORITY

TRAINING REPORTON

KHASA KOTHI FLYOVER

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JDA at a GlanceStrengthening Faith: Jaipur Development AuthorityJaipur Development Authority (JDA) has been committed to working forthe benefit of the citizens of Jaipur with planned implementation ofdevelopment schemes and is consistently striving to take Jaipur athigher levels of progress. Jaipur is one of the most well-plannedcities of its times and planned development has always been central toits ideology.Jaipur Development Authority came into existence by the Government ofRajasthan with a vision to combat and manoeuvre the growingrequirements of a large city in wake of the increasing population andto help give Jaipur a planned look compatible and comparable to anymetropolitan city of repute. JDA was authorised powers and a greensignal to speed up the development and progressive growth of theentire city to rapidly change the face of Jaipur. To meet theseimportant needs JDA sprang into action and started to understand thenecessary needs of the city.According to the requisites, JDA has been working towards time-boundconstruction, creation and development of the western part of Jaipurbased on major scientific and hi-tech strategies. Thus, Jaipur hasbeen beautified intensively to augment the tourist attraction in thecity and to raise the living standards to suit convenience of itscitizens.The major undertaking of JDA includes the following: * Infrastructural development of Jaipur region by construction offlyovers, 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. * Preparation and implementation of master plan. * Preparation and implementation of guidelines for colonisation. * Environmental development by planning and implementing roadsideplantations 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 ofdevelopment, creating a state-of-the-art city of substance. JDA hasbeen working on widening all main roads, construction of over bridges,under bridges and flyovers to regulate the traffic on roads, minimizepollution, and ensure public convenience and safety. JDA firmlybelieves in bridging the gap and reaching out to its citizens and toprovide them with quick and hassle-free service.

JDA...where town planning is a tradition.Contents1. Introduction2. Components of flyoveri) Foundationii) Piers and abutmentsiii) Deckiv) Pre-stressed concretev) Backfill and Reinforced earth wall3. Test reports

KHASA KOTHI FLYOVER

INTRODUCTIONThe Khasa Kothi flyover is being constructed at one of the busiesttraffic junction in jaipur city. The flyover is being constructed onthe road connecting the railway station to Sindhi Camp bus stand tofacilitate the easy movement of traffic plying from station to Chandpole, M.I. road & Banipark area. The cost of project is Rs. 22.0 Croreand length of fly over 740.0 Mts.The work was commenced after the stone laying on 30.10.06. The workwas stopped due to order passed by Hon’ble high court on 8.2.07 formaintaining status quo. This order was declared “non operative” byHon’ble high court on 30.05.07 and work restarted thereafter.The work worth Rs. 6.50 Crore has been done by 20th April 2009. Thesuper structure work is in progress and 80% of reinforced earth wallpanel has been casted. The work is proposed to be completed by July2010.

Salient FeaturesProject Cost : Rs. 2200.00 LacsAgency : M/s Harish Chandra (I) Ltd.Consultant : Span Consultant Pvt Ltd., DelhiWork order amount : Rs.19,63,69,312.00Stipulated date of commencement : 15.04.2006Stipulated date of completion : 14.10.2007Work Period : 18 MonthsDate of Start : 30.10.2006

Physical FeaturesTotal 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 : 14Service Roads : 5.5 Mts. On either side

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

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.MAJOR COMPONENTS OF FLYOVERFOUNDATIONSince the bridge has to carry a big live load and its dead weight isalso very large so we cannot go for simple foundation but pilefoundation.Pile foundation is one type of deep foundation. It is used where thegood soil is at higher depth (10 or 15m) or soil having low bearingcapacity. Pile is also used for tall structures. In pile foundationthe load coming from the super structure is taken by pile cap andequally distributed in no of piles, pile transfers this load into thesoil.The Khasa Kothi flyover consists of 115 bored cast in situ piles with14 pile caps.The diameter of each pile is 1200 mm with depth 25 meters anddifferent piers have different set of group of piles.

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

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.

INSTALLATION PROCEDURE OF PILESStep 1 --- Excavation of Pile ShaftThe bored pile equipment set including hydraulic oscillator, hydraulicvibrator, hammer grab and rock chisel used in this project is verycommon 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 obstructionsand then backfill, wherever necessary.c. Install the bottom section of temporary casing of required diameterinto the ground by oscillating and jacking or by vibrating motionexerted 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 steelcasing simultaneously by using the heavy duty casing oscillator /vibrator. Rock chisel in various types will be employed for removal ofobstruction or hard materials during the above process.f. Extend the steel casing by bolting or welding on additional casingduring the excavation.g. Water will be pumped into the casing during excavation and constantwater head will be maintained so as to prevent any ingress of materialfrom the bottom of casing.h. Verticality of the casing will be monitored by means of spiritlevel from time to time.i. Continue the above procedure until the founding level of pile hasbeen reached .j. Pile base enlargement will be formed by employing a bellout chiselor a reverse-circulation drill as indicated in the working drawings.

Step 2 --- Cleaning of Pile ShaftFinal cleaning will be carried out by the air-fitting method usinghigh pressure air compressors. The slime and muddy water within thecasing will be cleared and delivered into a desilting tank beforedischarge.

Step 3 --- Tremie Concretinga. The pile shaft will be concreted by "Underwater Tremie Technique".The tremie pipe sections will be inserted and be jointed until itreaches the bottom of pile shaft. Concrete will be poured into thetremie pipe by using a concrete skip. Concreting will be carried outin 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 aftereach skip of concrete is placed.c. The base of the tremie pipe will be kept with a minimum depth ofapproximate 1 to 2m below the surface of the concrete.d. The temporary casing will be extracted simultaneously by theoscillator in the course of concreting. A head is always maintainedbetween the top of concrete and the bottom of steel casing.

Step 4 --- Installation of ReinforcementAfter the completion of concreting, dowel bars of required length andnumbers will be installed into the pile shaft and down to thepredetermined level before the extraction of bottom steel casing.

PIERS & ABUTMENTSThe Khasa Kothi flyover has 15 piers including two abutments.The maximum height of the pier is about 6 m.

A typical Expansion joint used in bridge

DECKThe Khasa Kothi bridge is of box girder type bridge which is comprisedof prestressed concrete. The box is typically of trapezoidal incross-section. Compared to I-beam girders , box girders have a numberof key advantages and disadvantages.

Box girders offer better resistance to torsion, which isparticularly of benefit as the bridge deck is curved in plan. Additionally, larger girders can be constructed, because thepresence of two webs allows wider and hence stronger flanges to beused. This in turn allows longer spans. On the other hand, box girders are more expensive to fabricate, andthey are more difficult to maintain, because of the need for access toa 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 usingfalsework supports. First 75 m span is of solid type deck and then itconsists of box girders i.e. from A1 to P3 and P11 to A2 the deck issolid with the depth 1.2 m.The depth of box girder is different as per load requirement. From P3to 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 is16.75 m including 1m wide median and two crash barrier of width 0.375m.

Reinforcement pattern for box girder.

Pre-stressed ConcreteThe technique of pre-stressing eliminates cracking of concrete underall stages of loading and enables the entire section to take part in

resisting moments. As dead load moments are neutralized and the shearstresses are reduced, the sections required are much smaller than inreinforced concrete.Prestressing can be accomplished in three ways: pre-tensionedconcrete, and bonded or unbonded post-tensioned concrete.Pre-tensioned concretePre-tensioned concrete is cast around already tensioned tendons. Thismethod produces a good bond between the tendon and concrete, whichboth protects the tendon from corrosion and allows for direct transferof tension. The cured concrete adheres and bonds to the bars and whenthe tension is released it is transferred to the concrete ascompression by static friction. However, it requires stout anchoringpoints between which the tendon is to be stretched and the tendons areusually in a straight line. Thus, most pretensioned concrete elementsare prefabricated in a factory and must be transported to theconstruction site, which limits their size. Pre-tensioned elements maybe balcony elements, lintels, floor slabs, beams or foundation piles.Bonded post-tensioned concreteBonded post-tensioned concrete is the descriptive term for a method ofapplying compression after pouring concrete and the curing process (insitu). The concrete is cast around plastic, steel or aluminium curvedduct, to follow the area where otherwise tension would occur in theconcrete element. A set of tendons are fished through the duct and theconcrete is poured. Once the concrete has hardened, the tendons aretensioned by hydraulic jacks that react against the concrete memberitself. When the tendons have stretched sufficiently, according to thedesign specifications (see Hooke's law), they are wedged in positionand maintain tension after the jacks are removed, transferringpressure to the concrete. The duct is then grouted to protect thetendons from corrosion. This method is commonly used to createmonolithic slabs for house construction in locations where expansivesoils (such as adobe clay) create problems for the typical perimeterfoundation. All stresses from seasonal expansion and contraction ofthe underlying soil are taken into the entire tensioned slab, whichsupports the building without significant flexure. Post-tensioning isalso used in the construction of various bridges; both after concreteis cured after support by falsework and by the assembly ofprefabricated sections, as in the segmental bridge.

The advantages of this system over unbonded post-tensioning are:1. Large reduction in traditional reinforcement requirements astendons 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 strandand concrete.4. No long term issues with maintaining the integrity of the anchor/dead end.Unbonded post-tensioned concreteUnbonded post-tensioned concrete differs from bonded post-tensioningby providing each individual cable permanent freedom of movementrelative to the concrete. To achieve this, each individual tendon iscoated with grease (generally lithium based) and covered by a plasticsheathing formed in an extrusion process. The transfer of tension tothe concrete is achieved by the steel cable acting against steelanchors embedded in the perimeter of the slab. The main disadvantageover bonded post-tensioning is the fact that a cable can destressitself and burst out of the slab if damaged (such as during repair onthe slab).

The advantages of this system over bonded post-tensioning are:1. The ability to individually adjust cables based on poor fieldconditions (For example: shifting a group of 4 cables around anopening 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 unbondedpost tensioning system. In this system first of all high tensile steelcables/wires (also known as strands or tendons) encased in sheathingpipes were laid as per design and then concreting is done. After thehardening of concrete the stretching of wires was done by means ofhydraulic jacks. The jacking was done from both ends. The wires werejacked a few percent above their specified initial pre-stress in orderto minimize creep in steel and to reduce frictional loss ofpre-stress.The wires are anchored to concrete after stretching by wedge actionproducing a friction grip on wires.

Cables left for stressing before concrete is poured

We can see that the cables are in a grouped in every pipe. In theabove picture there are 19 cables in one group.

Sheathing pipes carrying cables.

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

Stretching of cables by hydraulic jack after hardening of concrete

The jack used in above picture has the capacity to stretch 4 cables ata time. This jack can perform both operations i.e. stretching of wireas well as tightening of wedges.

Calibrated pressure gauge to read directly the amount of tension applied

It is however the practice to measure the elongation of steel so thatthe magnitude of pre-stress can be calculated independently andchecked against the gauge reading.

Covering of cables after grouting

The cables are covered by concrete to prevent corrosion. The groutingis done through the hole as seen in above picture (in red circle) andthen the hole is then bolted as shown (in blue circle).

PROBLEMS LIKELY TO CAUSE DURING OR AFTER CONCRETING1. Segregation: Segregation of concrete can be defined as separationof coarse aggregate from mortar, resulting in their non-uniformdistribution. Improper mix proportion resulting in large proportion ofcoarse particles as compared to small proportion of fine particlescaused the separation of coarse particles from mortar. Segregation isalso caused by incorrect handling of mixed concrete duringtransportation and placement, and also by over-compaction.2. Honeycombing: The separation of coarse aggregate from mortar leavesvoids in coarse aggregate unfilled and this phenomenon is calledhoneycombing. Honeycombing causes decrease in the density of concreteand hence reduction in the strength of the concrete.3. Bleeding: Bleeding is a form of segregation in which water in aconcrete mix rises to the surface during placing it. It is becausemore water is present than is necessary for the cement paste tolubricate the aggregate particles and the solid constituents of themix are able to hold all the mixing water when they settle down. Thus

the water rises up and appears on the surface of the compactedconcrete. Sometimes, finer particles such as cement are also carriedwith the rising water. The water trapped by the superimposed concreteresults in a porous weak and the non-durable concrete. If the risingwater is trapped on the underside of reinforcement, then a zone ofpoor bond is created. This water form voids on evaporation and makesthe concrete weaker.

PRECAUTION TO BE TAKEN DURING PLACING OF CONCRETE:1. Under no circumstances, the water should be added to the concreteduring its passage from mixer to the formwork2. The formwork or the surface which is to receive the fresh concreteshould 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 insuccessive horizontal layers and proper care should be taken todevelop enough bonds between successive layers.4. The concrete should be thoroughly worked around the reinforcementand tapped in such a way that no honeycombed surface appears onremoval 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 ofconcrete surface remain unbroken, sharp and straight in line.7. The placing of concrete should be carried out uninterrupted betweenpredetermined construction joints.

CONSOLIDATION OF CONCRETE:The main aim of consolidation of concrete is to eliminate air bubblesand thus to give maximum density to the concrete.In Khasa Kothi flyover the Internal or Immersion vibrators are usedfor consolidation of concrete. These vibrators consist of a steel tubewhich is inserted in fresh concrete. This steel tube is called thepoker and it is connected to an electric motor. The poker vibrateswhile it is being inserted. The internal vibrators should be insertedand withdrawn slowly and they should be operated continuously whilethey are being withdrawn. Otherwise holes will be formed inside theconcrete.

BACKFILL AND REINFORCED EARTH WALLReinforced earth is a composite material formed by the frictionbetween the earth and the reinforcement. By means of friction the soiltransfers to the reinforcement the forces built up in the earth mass.The reinforcement thus develops tension and the earth behaves as if ithas cohesion. Reinforced members are composed of thin wide strips alsocalled as ties.For reinforcement the GI strips are used which are 40 mm wide and 5 mmthick and the length varies as according to the tensile stresses atvarious place and levels.The facing elements for backfill are precast concrete panels havingdimension 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 andthe moisture content was kept at 8 to 9%.ProcedurePlace and compact initial lifts of select Granular backfill up tobottom row of panel tie strips. The level of the compacted backfillshould be 50mm above the tie strips. In order to avoid pushing thebrace panels out of alignment, initial lifts of backfill are neitherplaced nor compacted against the back of the panels. Compact eachbackfill lift using a large smooth-drum vibratory roller except withina 100 cm zone directly behind the panels where a small hand-operatedvibratory compactor must be used to avoid undue panel movement.After compaction has taken place, check wall alignment visually andwith a level adjust panels as necessary.A drainage system is made near panels by laying 20mm coarse aggregatesnear panels up to a width of 60 cm throughout the depth and at thebottom a semi perforated pipe is used to drain out the water.Immediate gradation and moisture testing is required if eitherexcessive panel movement or backfill pumping occurs duringconstruction.

Compaction: Large smooth-drum vibratory rollers are used to accomplishmass 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 a 425 µ

sieve used for backfill, must be compacted using a smooth drum staticroller.Vibratory compaction equipment should not be used to compact fine uniform sands.Moisture content of backfill material during placement should beapproximately 1% to 2% more than its optimum moisture content.Reinforcing Strips:-Place reinforcing strips on the compacted backfill. Position stripsperpendicular to the facing panels, unless otherwise shown on theplans. Reinforcing strips are supplied in lengths as shown on plans.Connect each reinforcing strip to the embedded panel tie strip byinserting the end of the reinforcing strip into the gap between thetwo exposed ends of the tie strip. Match the three holes and push abolt through the holes from below, threading on a nut and tightening.Dump backfill onto the reinforcing strips so that the toe of thebackfill pile is 3-4 ft from the panels. Spread the backfill bypushing the pile parallel to the panels.Metal tracks of earthmoving equipment must never come in contact withthe reinforcing strips. Rubber-tired vehicles, however, can operatedirectly on the exposed strips if backfill conditions permit and careis exercised.At the joints of panels a special type of semi permeable textile knownas geo-textile is used to stop the backfill from slipping out of thepanels.

Spreading of backfill

In the above picture we can see the arrangement of panels. No bindingmaterial is used to join the panels they are interlocked with eachother.

GRADATION FOR COARSE AGGREGATE

TYPE OF AGGREGATE 20mm Date:- 30-05-09TOTAL WEIGHT TAKEN 2922 GmsSieve Size Weight Retained % Retained %Cumulative Retained %Passing Remarks25 0 0.00 0.00 100.0020 172 5.89 5.89 94.1110 2662 91.10 96.99 3.014.75 68 2.33 99.32 0.68Pan 20

TYPE OF AGGREGATE 10mm Date:- 30-05-09TOTAL WEIGHT TAKEN 2957 GmsSieve Size Weight Retained % Retained %Cumulative Retained %Passing Remarks12.5 0 0.00 0.00 100.0010 268 9.06 9.06 90.944.75 2514 85.02 94.08 5.922.36 120 4.06 98.14 1.86Pan 55

Sieve Size For 20 mm For 20 mm Combined Grading As per IS 383 %Passing %Passing %Passing %Passing Lower Limit Upper Limit20 100% 63% 100% 37%10 94.11 59.29 100 37.00 96.29 95 1004.75 3.01 1.90 90.94 33.65 35.54 25 55Pan 0.68 0.43 5.92 2.19 2.62 0 10

GRADATION FOR COARSE AGGREGATE

TYPE OF AGGREGATE SAND Date:- 30-05-09TOTAL WEIGHT TAKEN 531 Gms

Sieve Size Weight Retained % Retained %CumulativeRetained %Passing Remarks Zone II4.75 12 2.26 2.26 97.74 90-1002.36 28 5.27 7.53 92.47 75-1001.18 65 12.24 19.77 80.23 55-900.6 190 35.78 55.56 44.44 35-590.3 157 29.57 85.12 14.88 8-300.15 69 12.99 98.12 1.88 0-10

PAN 10

AS PER IS 383 SAND IS IN ZONE II