ACKNOWLEDGEMENT

We express our sincere thanks to some without their assistance this work could not be undertaken at all. We convey our deep sense of gratitude to

For providing us the opportunity to take up this project.

We own the most diverse and deepest gratitude to our guides who have spent their valuable time and effort to help us to give information about the project.

We are thankful to Sri.B.G.M.K.Chari, DGM (Civil)/S.M.S (Construction) for his esteemed guidance throughout the project. We extend our sincere thanks to Mr.V.S.N.Raju, Asst. Manager (Civil)/S.M.S (Construction) for giving us technical insight about the project aspects in particular. We are also thankful to Mr.V.Ravi Kumar, M.N.Dastur & Co. for his valuable guidance and acquaintance of various civil structures at site.

Lastly we are also thankful to Mr.J.Prabhakar Rao, Asst. Manager (T&DC), VSP for posting us at SMS construction zone for the study.

TABLE OF CONTENTS

SL. NO. TITLE PAGE

1. INTRODUCTION 4

2. STEEL PLANT OVERVIEW 7

3. REVIEW OF LITERATURE 13

4. CONSTRUCTION OF BORED CAST-IN-SITU PILES

Specification for bored RCC piles 25

Piling work 27

Workmanship 30

Construction of Pile 32

Properties of Bentonite 39

Pile load tests 42

5. CONCLUSION 54

6. BIBLOGRAPHY 56

1 | P a g e

ABSTRACT

Technology developments in the field of construction has put more challenges to the

infrastructure to sustain the severe development of industries and of large scale building of

highways, bridges, tunnels & dams.

Apart from this Civil Engineering have many diverse and important encounters with soil. It

is particularly helpful in the design of foundations, rigid and flexible pavements,

underground and earth retaining structures, embankments and excavations.

The loads from any structures have to be ultimately transmitted to soil through the

foundation of the structure. Thus the foundation is an important part of a structure, the type

and details of which can only be decided upon with the knowledge and application of the

principles of soil mechanics.

Knowledge of soil mechanics is a prerequisite to be a successful foundation engineer.

In the present study entitled “Construction of Bored cast-in-situ piles”, we study about the

various aspects related to the construction procedures of bored pile foundations that are

constructed at VISAKHAPATNAM STEELPLANT, materials used in the construction of

piles and various load tests.

2 | P a g e

INTRODUCTION

3 | P a g e

INTRODUCTION

Civil engineers may construct many types of structures to serve various infrastructural

requirements and these include infrastructural buildings, dams, bridges, roads, railway

lines and related structures, ports etc.

All these structures are designed to transmit load to the soil on which they rest. To enable

the stress to be safely transferred to the soil, these structures are soil linked and called

foundation. The size and shape of the foundation determines the stress that is finally

transferred to the soil underneath. Once the size and shape are determined, the substructure

or the foundation is to be structurally designed to withstand the load of the superstructure

on one side and the reaction from the soil from the outer side.

A foundation should be designed such that the soil below doesn’t fail in shear. The

settlement which the soil can safely withstand is known as allowable bearing pressure.

There are generally two types of foundations:

1. Shallow foundations

2. Deep foundations

1. SHALLOW FOUNDATIONS:

Shallow foundations are the most common type of foundations and can be laid using

open earth excavation by allowing natural slopes on all sides. These are also called

“Open foundations”. These types of foundations are for depths of 2 to 3 meters and

4 | P a g e

are normally convenient foundations, provided for structures of moderate height

built on soils having satisfactory amount of bearing capacity.

2. DEEP FOUNDATIONS:

When the foundations have to carry heavy structural loads through a weak

compressible soil, the foundations are called “Deep foundations”. These are of two

types:

Pile foundations

Well foundations

PILE FOUNDATIONS:

A pile may be defined as a long vertical load transferring elements composed of timber,

steel, concrete or combination of them.

Piles are used to carry vertical loads through weak soil to dense strata having high bearing

capacity. In normal ground conditions, they can resist large uplift and horizontal loads,

hence, can be used as foundations of multistoried buildings, transmission line towers,

retaining walls, bridge abutments.

Pile foundations are adopted in the following situations:

Low Bearing Capacity of soil .

Non availability of proper bearing stratum at shallow depths.

5 | P a g e

Heavy loads from the super structure for which shallow foundation may not be

economical or feasible.

When the plan of structure is irregular relative to its outline and distribution

It would cause non uniform settlement if a shallow foundation is constructed. A pile

foundation is required to reduce differential settlement.

Pile foundations are required for the transmission of structural loads through deep

water to a firm stratum.

Pile foundations are used to resist horizontal forces in addition to support the vertical

loads in earth retaining structures and tall structures that are subjected to horizontal

forces due to wind and earthquake.

Piles are required when the soil conditions are such that a washout, erosion or scour

of soil may occur from underneath a shallow foundation.

Piles are used for foundations of some structures such as transmission towers, off-

shore platforms which are subjected to uplift.

In case of expansive soils such as black cotton soils, which swell or shrink as water

content changes, piles are used to transfer the below the active zone.

6 | P a g e

STEEL PLANT

OVERVIEW

7 | P a g e

VISAKHAPATNAM STEEL PLANT OVERVIEW

Visakhapatnam steel plant is one of the prestigious steel plants in India which is located at

Visakhapatnam of Andhra Pradesh.

VSP is only shore based steel plant in India. It is of 3 million metric tons capacity per

annum with sophisticated technology. It is only steel plant to get all ISO certificates like

ISO 9001, ISO 14001, ISO18001 and 5s certificates for 53 departments ERM [Enterprise

Risk Management] and ERP [Enterprise Resource Planning] are also in implementation

stage. It won Prime Minister Trophy for 2 times. Visakhapatnam steel plant is also called

"Jewel of Andhra Pradesh”. Foundation stone was laid by late Prime Minister Smt. Indira

Gandhi.

1. Visakhapatnam steel plant, the first coastal based steel plant of india is located 16km

south west of city of destiny, i.e. Visakhapatnam. The site is situated south of

National Highway no.5 and the east coast Railway line between Visakhapatnam and

Chennai sea level (MSL). The plant site located at latitude of 17°37’N and longitude

of 83°12J E.

2. CLIMATE OF VISAKHAPATNAM:-

The climatological dates on vicinity of the site are as follows:

RAINFALL:-

Highest monthly : 606 mm

Highest daily : 370 mm8 | P a g e

Highest recorded temp : 40.50 C

Lowest recorded temp : 16.50 C

Relative humidity : 4%(min) to 100% (max)

Wind velocity : 32.5 kmph (highest monthly wind speed fir 24hr)

3. EARTHQUAKE FACTOR:-

This plant is falling under Zone II as per IS: 1893.

4. RAILWAYS:-

The nearest railway station is Duvvada on the Visakhapatnam Chennai line about

10km from the plant and the Visakhapatnam railway station is about 30km from the

plant.

5. ROADS:-

The national highway passes beside the plant.

6. SEAPORT:-

The nearest seaport at Visakhapatnam is about 16 km from the plant site. A new port

at Gangavaram is under development and it is adjacent to the north east boundary

me the plant.

9 | P a g e

7. AIRPORT:-

The nearest airport at Visakhapatnam is about 12 km from the plant.

8. COMUNICATION:-

Postal and other telecommunication facilities are well established in Visakhapatnam.

VSP by successfully installing & operating efficiently Rs.460 crores worth of

pollution control & environmental control equipment and converting the barren

landscape by planting 3 million plants has made the steel plant , steel township and

surrounding areas into a heaven of lush greenery.

VSP exports quality pig iron & steel products to Sri Lanka, Myanmar, Nepal,

Middle East, USA& south East Asia. RINL-VSP was awarded “Star trading house”

status during 1997-2000 having established a fairly dependable export market.

Having a total manpower of 17000, VSP has envisaged a labour productivity of

not less than 230 per man year of liquid steel which is the best in the country and

comparable with international levels.

Steel is one of the most important components that can strengthen the economic

backbone of any country.

EXPANSION PROJECT

Introduction:-

1. Visakhapatnam steel plant (VSP) is an integrated public sector steel plant owned by

Rashtriya Ispat Nigam limited(RINL), built an annual production capacity of about 3

million tons of liquid steel per year with provisions for future expansion.10 | P a g e

2. The detailed project report was prepared by the principal consultant, M.N.Dastur

&Co.(P)Ltd in 1980. The project has envisaged iron making capacity of 3.4mtpy,

2.66mtpy including 0.246mtpy of saleable billets. The iron and steel making

facilities were generally based on the utilization of soviet equipment, while rolling

mills were from other sources.

3. VSP has been able to achieve hot metal production of about 4mtpy from its two blast

furnaces for the last two years. Steel melt shop has also been able to produce about

3.5 million tons of liquid steel, 3.17mtpy of saleable steel, out of which for sale

constituted about 0.18 million tons in 2003-04.

4. Keeping in view the upturn in global and domestic steel demand, VSP is envisaging

increasing their plant capacity to about 605 mtpy of hot metal initially, followed by

commensurate increase in production of liquid and saleable steel. Future plan

envisages increase in plant capacity to about 10mtpy.

Construction volume:-

5. The quantum of major construction work involve in 6.5mtpy stage is given in table:

QUANTITIES OF CONSTRUCTION WORK

Item of work Unit Quantity

Piling 600mm dia 120 ton capacity nos 26,100

Concreting of all grades cum 700,000

Structural steel work ton 185,00011 | P a g e

Equipment erection ton 102,000

Pollution control and environmental protection:-

6. Adequate pollution control and environmental protection measures have been

considered for this plant arising out of the expansion plans. Due consideration has

been given to water, environmental protection, work-zone pollution control, solid

by-products management, plant safety, greenbelt & landscaping environmental

monitoring.

Conclusion:-

7. From the financial results projected above, it can be concluded that the project is

very attractive and will place RINL in the topmost bracket of earning potentiality.

12 | P a g e

REVIEW OF

LITERATURE

13 | P a g e

REVIEW OF LITERATURE

Terminology:

Raker Pile: - The pile which is installed at an angle to the vertical.

Bearing Pile: - A pile formed in the ground for transmitting the load of structure to the soil

by the resistance developed at its tip and/or along its surface. It may be formed either

vertical or at an inclination (Batter Pile) and may be required to take uplift. If the pile

supports the load primarily by resistance developed at the pile point or base it is referred to

as ‘End Bearing Pile’; if primarily by friction along its surface, then as ‘Friction Pile’.

Bored Cast-in-situ Pile:-The pile formed within the ground by excavating, with or

without the use of a temporary casing and subsequently filling it with plain or reinforced

concrete. When the casing is left permanently it is termed as “cased pile” and when the

casing is taken out it is termed as “uncased pile”.

In installing a bored pile the sides of the borehole (when it does not stand by itself)

is required to be stabilized with the aid of a temporary casing, or with the aid of drilling

mud of suitable consistency. For marine situations such piles are formed with permanent

casing (liner).

Cut-Off Level: - It is the level where the installed pile is cut-off to support the pile caps or

beams or any other structural components at that level.

14 | P a g e

Working Pile: - A pile forming part of foundation of a structural system.

Net Displacement:-The net movement of the pile top after the pile has been subjected to a

test load and subsequently released.

Test Pile:-A pile which is selected for load testing and which is subsequently loaded for

that purpose. The test pile may form working pile itself, if subjected to routine load test

with loads up to one and one half times the safe load.

Trial Pile:-Initially one or more piles, which are not working piles, may be installed to

assess load carrying capacity of a pile. Pile of this category is tested either to its ultimate

load capacity or to twice the estimated safe load.

Total Elastic Displacement:-This is the magnitude of the displacement of the pile due to

rebound caused at the top after removal of a given test load. This comprises two

components:

a) Elastic displacement of the soil participating in the load transfer.

b) Elastic displacement of the pile shaft.

Total Displacement (Gross):- The total movement of the pile top under a given load.

Ultimate Load Capacity: - The maximum load which a pile can carry before failure of

ground (when the soil fails by shear).

Datum Bar: - A rigid bar placed on immovable supports.

Kentledge: - Dead-weight used for applying a test load on piles.

15 | P a g e

Routine Test: It is carried out on a working pile with a view to check whether pile is

capable of taking the working load assigned to it.

PILE FOUNDATION:

Piles find application in foundation to transfer loads from a structure to competent

subsurface strata having adequate load bearing capacity. The load transfer mechanism from

a pile to the surrounding ground is complicated and could not yet be fully ascertained,

although application of piled foundations is in practice over many decades.

Broadly, piles transfer axial loads either substantially by skin friction along its shaft

or substantially by the end bearing. Piles are used where either of the above load transfer

mechanism is possible depending upon the subsoil stratification at a particular site.

Construction of pile foundations require a careful choice of piling system depending upon

the subsoil conditions, the load characteristics of a structure and the limitations of total

settlement, differential settlement and any other special requirement of a project.

16 | P a g e

Piles are classified into many types depending on the materials used, the mode of transfer

of load, the method of construction, the use, displacement of soil, sectional area and size as

described below.

Classification based on materials used:

Steel piles

Concrete piles

Timber piles

Composite piles

Classification based on use:

Load bearing piles

Compaction piles

17 | P a g e

Tension piles

Sheet piles

Fender piles

Anchor piles

Classification based on Load Transfer Mechanism:

End-bearing piles

Friction or floating piles

Combined end-bearing and friction piles

Classification based on displacement of soil:

Displacement piles

Non-displacement piles

Classification based on Method of Installation:

Driven precast piles

Driven cast-in-situ piles

Bored precast piles

Bored cast-in-situ piles

18 | P a g e

Classification based on sectional area:

Circular

Square

Octagonal

H

Tubular

Classification based on size:

Micro piles dia < 150mm

Small dia pile dia 150 to 600mm

Large dia pile dia > 600mm

Classification based on Inclination:

Vertical Piles

Inclined or Raker Piles

Loads coming on pile foundation:

All the loads from super structure viz. Dead loads, Live loads Wind loads and

Seismic loads.

The loads from the surrounding soil in case of seismic event.

Water loads in the case of off-shore structures.

Load carrying mechanism of piles:19 | P a g e

End bearing cum friction piles carry vertical compressive loads partly by means of

resistance offered by the hard stratum at the tip of the pile and partly by the friction

developed between the pile shaft and soil.

Pure friction piles carry the major part of loads only by means of friction developed

between pile shaft and soil; and pure End bearing piles only by means of bearing

resistance at the tip of the pile.

In both the above cases lateral loads are carried by the lateral resistance offered by the

surrounding soil.

BORED PILE:

Bored pile is a type of reinforced concrete pile, which is used to support high building

producing heavy vertical loads.

Bored pile is a cast-in-place concrete pile where the bored piles have to be cast on the

construction site, while other concrete piles like Spun Pile and Reinforced Concrete Square

Pile are precast concrete piles.

Bored piling is cast by using bored piling machine which has specially designed

drilling tools, buckets and grabs, it’s used to remove the soil and rock. Normally, it can be

drilling into 50 meters depth of soil. The advantage of bored piling is its drilling method, little

vibration and lower noise level.

The drilling method depends on the condition of soil, piling contractor has to do soil

investigation and decide which drilling technology has to be carried on. Piling contractor

decides the correct drilling technology and minimize disturbance of the surrounding soil. For

20 | P a g e

cohesion-less soils such as sands, gravels, silts, etc., whether it’s under the water table or not,

the pile bore hole must be supported using steel casing or stabilizing mud such as bentonite

suspension.

Rotary boring techniques offer larger diameter piles than any other piling method

and permit pile construction through particularly dense or hard strata. Construction

methods depend on the geology of the site. In particular, whether boring is to be

undertaken in 'dry' ground conditions or through water-logged but stable strata i.e. 'wet

boring'.

For end-bearing piles, drilling continues until the borehole has extended a sufficient

depth (socketing) into a sufficiently strong layer. Depending on site geology, this can be a

rock layer, or hardpan, or other dense, strong layers. Typical socket depths are equal to the

diameter of the pile in hard rock layers and 2.5 times the diameter of the pile in soft rock

layers.

'Dry' boring methods employ the use of a temporary casing to seal the pile bore

through water-bearing or unstable strata overlying suitable stable material. Upon reaching

the design depth, a reinforcing cage is introduced; concrete is poured in the borehole and

brought up to the required level. The casing can be withdrawn or left in situ.

'Wet' boring also employs a temporary casing through unstable ground and is used

when the pile bore cannot be sealed against water ingress. Boring is then undertaken using

a digging bucket to drill through the underlying soils to design depth. The reinforcing cage

is lowered into the bore and concrete is placed by tremie pipe, following which, extraction

of the temporary casing takes place.

21 | P a g e

A common mode of failure for drilled piles is formation of a reduced section due to

the collapse of the walls of the shaft during installation, reducing the pile capacity below

applied loads. Drilled piles can be tested using a variety of methods to verify the pile

integrity during installation.

Advantage of bored piles:

Length can readily be varied to suit variation in level of bearing stratum.

Soil or rock removed during boring can be inspected for comparison with site

investigation data.

In-situ loading tested can be made for large diameter pile bore holes.

Very large bases can be formed in favorable ground.

Drilling tools can break up boulders or other obstructions which cannot be penetrated

by any form of displacement piles.

Material forming pile is not governed by handling or driving stresses.

Can be installed in very long lengths without appreciable noise or vibration and no

ground heave.

Can be installed in conditions of low headroom.

22 | P a g e

Disadvantages:

Concrete in shaft is liable to squeezing or necking in soft soils where conventional

types are used.

Special techniques are needed for concreting in water bearing soils.

Concrete cannot be inspected after installation.

Enlarged base cannot be formed in cohesion less soils.

Cannot be extended above ground level without special adaption.

23 | P a g e

CONSTRUCTION OF

BORED

CAST-IN-SITU

PILES

24 | P a g e

SPECIFICATION FOR BORED CAST-IN-SITU REINFORCED

CEMENT CONCRETE PILES

GENERAL:

Surveyed by total station survey instrument.

Survey checked by traverse method.

Soil and site condition.

Soil strata are varying. Here it is mainly metallurgical waste. The soil is up to 7 to 9m.

The local site and traffic condition is good. Site is connected to road which is from the

way of rolling mills and other through project plaza gate.

BORED CAST-IN-SITU REINFORCED CEMENT CONCRETE PILES:

SCOPE OF WORK:

The work covered under this specification includes provision and installation of

bored cast-in-situ reinforced concrete piles of different to competent rock strata.

Routine load test on piles, pile integrity test are specified.

And equipment collection of soil samples of various strata and founding rock layer,

measurements of final depth and bored diameter etc., complete as specified.

25 | P a g e

The piles shall be cast with grade of concrete and reinforcement as specified and by

suitable method approved by consultant and samples of concrete shall be taken for

testing in an approved laboratory.

The scope of pile testing shall include excavation to required depth and size,

placement of kentledge, reaction loading, reaction blocks or frames for vertical

compression, pill-out and lateral load tests, preparation of pile heads by breaking and

chipping up to specified test level and making good the same for load testing and

conducting routine load test of working piles.

Integrity test shall be carried out on a number of selected piles to detect any defects

like cracks, intrusion and diameter changes etc., if any on pile shaft.

EQUIPMENT AND ACCESSORIES:

The equipment and accessories would depend upon the type of bored

cast-in-situ piles chosen in a job and would be selected giving due consideration to the

subsoil strata, ground water conditions, type of founding material and the required

penetration therein wherever applicable. Among the commonly used plants, tools and

accessories, there exist a large variety, suitability of which depends on the subsoil

conditions and manner of operations, etc.

Boring operations are generally done by rotary or percussion type drilling rigs using

direct mud circulation or reverse mud circulation methods to bring the cuttings out.

26 | P a g e

In soft clays and loose sands bailer and chisel method, if used, should be used with

caution to avoid the effect of suction. Rope operated grabbing tool or Kelly mounted

hydraulically operated grab are also used. The grab method of advancing the hole avoids

suction. The size of the cutting tool should not be less than the diameter of the pile by more

than 75 mm.

PILING WORK:

1. General:

Piles shall be bored cast-in-situ reinforced concrete type with safe load bearing

capacities as stated below:

Pile diameter (mm) Capacity (tons)

400 55

600 120

1000 300

Cement:

For piling work, Blast Furnace Slag Cement shall be used. Ordinary Portland

cement of 43 grade shall be used with prior approval from consultant; if there is any doubt

in the quality of cement, sample for testing are sent to employer’s testing laboratory.

Cement shall be stored on raised platforms inside stores covered on all sides and roof with

provision for ample ventilation. Different types of cements shall be stored separately and

more than 10 bags of cement shall not be stacked one above the other in the stack. It is so

arranged that the bags from the oldest consignment in the stack can conveniently be

removed first for use on first in first out (FIFO) basis. Cement which is hardened, clodded

or deteriorated due to over stacking or long storage shall not be used in works and shall be

removed from site immediately.

27 | P a g e

Aggregates:

All aggregates shall confirm to IS: 383. Coarse aggregates shall be approved

crushed stone or gravel washed clean. Fine aggregates shall be river or pit sand. Coarse and

fine aggregates shall be stored at site separately on clean and hard base or in separate

compartments or hoppers. Samples of aggregates to be used shall be submitted to the

consultant for approval before commencement of work. No aggregate shall be used without

prior approval of the consultant. If necessary, grading of aggregates shall be maintained by

blending different sizes of aggregates that shall be brought to site and stacked in separate

stock piles. Sampling of aggregates shall confirm to IS: 2430 and tests shall confirm to IS:

2386. The percentage of flaky and elongated pieces should not exceed 15%.

Reinforcement:

MS round bars shall confirm to grade I of IS: 432- mild steel and medium tensile

steel bars and deformed bars shall confirm to IS: 1786- high strength deformed steel bars

(Fe 415). All reinforcements shall be free from oil, paint, loose rust, mill scale or other

matters likely to weaken or destroy their bond with concrete.

Binding wire:

Binding wire shall be approved 20 SWG annealed iron wire.

Water:

Water shall be clean and potable quality of pH value ranging between 6 to 8.

Bentonite:

Bentonite shall confirm to appendix A of IS: 2911(Part-1/Section-2).

28 | P a g e

2. CONCRETE MIX:

The concrete shall be controlled concrete as defined by IS: 456 and IS: 2911(Part-

1/Section-2). The grades of concrete shall be specified and the strength requirements shall

be in accordance with IS: 456.

Aggregates in each mix of concrete shall be graded and the water cement ratio

controlled in accordance with IS: 456 and frequent tests are conducted to ensure the usage

of correct grade of concrete.

3. MIXING:

All components of concrete shall be proportioned by weight for each grade. Mixing

shall be done in a concrete batching plant.

Consistency: Consistency of concrete for cast-in-situ piles shall be suitable to the

method of installation of piles. Concrete shall be so designed or chosen as to have

homogeneous mix having a flow able character consistent with the method of

concreting under the given conditions of pile installation. In achieving these results,

minor deviations in the mix proportions used in structural concrete may be

necessary.

Tests: Sampling, mixing, curing and testing of concrete specimens shall comply

with IS: 456, 516 and 1199.

4. CONCRETE:

Materials and methods of manufacture for cement concrete shall in general be in

accordance with the method of concreting under the conditions of pile installation.

29 | P a g e

For pile of smaller diameter and depth of up to 10 m, the minimum cement content

should be 350 kg/m3 of concrete. For piles of large diameter or deeper piles, the minimum

cement content should be 400 kg/m3 of concrete.

For design purposes, the strength of concrete mix using the quantities of cement

mentioned above may be taken equivalent to M 15 and M 20.

Where concrete of higher strength is needed, richer concrete mix with greater

cement content may be designed. In case of piles subsequently exposed to free water or in

case of piles where concreting is done under water or drilling mud using methods other

than the tremie, 10% extra cement over that required for the design grade of concrete at the

specified slump shall be used subject to a minimum quantity of cement specified.

Slump of concrete shall range between 150 to 180 mm where concrete is to be

placed under drilling mud by tremie.

Plasticizers or retarders of approved makers may be necessary for ease of concreting

shall be provided.

WORKMANSHIP:

Control of Pile Installation:

Bored cast-in-situ reinforced concrete piles shall be capable of being tested for load

carrying capacity after 28 days of casting. Bored cast-in-situ piles shall be constructed by

suitable choice of installation techniques i.e., use of casing and/or use of drilling mud;

manner of concreting i.e., direct pouring and placing or by use of tremie, choice of boring

tools in order to permit satisfactory installation of a pile at a given site. Sufficient detailed

information about the subsoil conditions is essential to predetermine the details of the

installation technique.

30 | P a g e

Control of Pile Alignment:

Piles shall be installed as accurately as possible as per the designs and drawings

either vertically or to the specified batter. Greater care should be exercised in respect of

installation of single pile or piles in two pile groups.

Displacement - shall not exceed 75mm in any direction from its

true position as approved on drawing.

Verticality - shall not deviate more than 1.5% for vertical piles shall not

deviate more than 4% for raker piles.

In the case of a single pile in a column positional tolerance should not be more than

50 mm (100 mm in case of piles having diameter more than 600 mm). Greater tolerance

may be prescribed for piles driven over water and for raking piles.

Any piles deviating beyond limits and to such an extent that the resulting

eccentricity cannot be taken care of by a redesign of the pile cap of pile ties, the piles

should be replaced or supplemented by one or more additional piles.

31 | P a g e

Construction of Pile:

Rotary Piling Rigs:

The pile boring rigs shall be crawler mounted, hydraulically or mechanically

operated rotary rig with capability for accessories attachments i.e., compressed air

pulveriser, oscillating type liner, different cutting tools etc., or equivalent capable of

drilling or boring through hard compact slag, soft or weathered as well as sound rock with

necessary mud circulation technique. These rigs shall preferably be light, easy to transport

and fully self-erecting so that they can be set up quickly without the aid of auxiliary cranes.

The rigs shall consist of telescopic leaders or Kelly bars expandable tracks and a low

32 | P a g e

Centre of Gravity. The engines generate enough torque (5 to 25 t-m) to bore through hard

compacted slag and sound hard rock at high speed.

Adequate hydraulic steam adaptable to different equipment like hammers, rotary

heads, augers, vibratory heads etc., shall be an essential feature of such rigs.

Tripod Rigs:

Conventional tripod rigs with bailer-chisel arrangement with provision of installing

casings up to depths as necessary based on site condition and equipped with Direct Mud

Circulation (DMC) arrangements shall be deployed.

Boring:

In general, piles bores shall be kept cased with lead-in-tube to prevent ingress of soil

followed by temporary casing to required depth. Minimum length of temporary casing

during boring, if required, using conventional tripod rig, shall be 1.5m. However, actual

length of casing in all cases will depend upon the requirements based on site condition. In

the present site boring was done up to 14 m and casing was inserted up to 6m maintaining

the centre by reference points and also maintaining the level. Inflow of ground water and

soil shall be controlled and sides of bore holes stabilized by using sufficient head of

drilling mud such as bentonite suspension. The head of bentonite slurry shall be kept at

least one metre (1m) above the standing water level.

Pile dia. Minimum depth of Stock length into

(mm) into compact hard rock(mm)

400 800 (2d)

600 1200 (2d)

33 | P a g e

1000 2000 (2d)

Final depth of boring shall be determined by sounding and in case of uncased bores,

diameter of bore at different depths shall be determined by a pantograph or other suitable

means. After completion of boring the bore hole shall be cleaned by controlled air-lift

method of finishing with fresh drilling fluid.

Lowering of reinforcement cage:

On satisfactory completion of boring, the reinforcement cage shall be lowered inside

the bore hole with sufficient numbers of round cement concrete cover blocks attached to

the lateral links. The lap length and the spiral shall be tack welded to the main

reinforcement. The reinforcement cage should go down into the bore hole and in no case

the cage shall be allowed to withstand on its own from bottom of bore to avoid buckling.

Precaution shall be taken to ensure that the cover blocks do not get damaged during cage

lowering.

The minimum clear cover to all main reinforcement in pile shaft shall be not less than

40mm. The minimum clear distance between two adjacent main reinforcement bars should

normally be 100 mm for the full depth of the cage or spirals.

The laterals of a reinforcing cage may be in the form of links

The diameter and spacing of the same is chosen to impart adequate rigidity of the

reinforcing cage during its handling and installation.

34 | P a g e

Concreting:

Concreting operations shall not be taken up when the specific gravity of the bottom

slurry is more than 1.12. Concreting shall be done by tremie method in all such cases. The

slurry shall be maintained at least 1.5m above the ground water level if casing is not used.

The temporary casing may not be required except near the top when concreting

under drilling mud. The hopper and tremie should be a closed system embedded in the

placed concrete, through which water cannot pass. The tremie should be large enough with

due regard to the size of the aggregate.

35 | P a g e

Bottom of the bore hole shall be cleaned of all accumulated sand, muck and loose

materials by controlled air-lift flushing with fresh drilling fluid. The tremie pipes shall

extend to the bottom of bore hole at start and shall be joined in sections and fitted with the

hopper for receiving concrete poured at the top of the opening.

The first charge of hopper shall be poured in hopper with bottom opening

temporarily closed by a steel plate placed at top of the opening. The hopper shall have

adequate capacity to receive the volume of concrete sufficient enough to displace drilling

mud within tremie pipe and from bottom of bore hole. After the hopper is filled up the steel

plate shall be quickly removed to allow concrete to rush into pile bore and fill it up from

bottom by displacing the drilling fluid from tremie pipe and the bottom of bore hole.

As the concreting progresses, the tremie pipes shall be removed in sections ensuring

every time that the bottom of tremie pipe remains embedded for atleast one metre (1m) into

concrete. Placing of concrete shall be done in one continuous operation and the tremie

pipes shall be held concentric with the bore hole.

In the exceptional case of interruption of concreting; but which can be resumed

within 1 or 2 hours, the tremie shall not be taken out of the concrete. Instead it shall be

36 | P a g e

raised and lowered slowly, from time to time to prevent the concrete around the tremie

from setting. Concreting should be resumed by introducing a little richer concrete for easy

displacement of the partly set concrete.

Level of concrete shall be checked at frequent intervals to maintain a sufficient head

of concrete above the discharge end of mixes are poured to expel the fresh mix of concrete

contaminated with bentonite such that good concrete is obtained atleast up to 150mm

above the cut-off level. At all stages of concreting care shall be taken to prevent voids and

segregation in concrete.

The top of concrete in a pile shall be brought above the cut-off level to permit

removal of all laitance and weak concrete before capping and to ensure good concrete at

the cut-off level.

Withdrawal of casing:

Extraction of casing pipes shall be done in such a way that no necking or shearing of

concrete in shaft takes place.

Sequence of Piling:

Sequence of piling shall be such that there is no damage caused to concrete recently

laid in adjacent pile. Construction of pile should be done in accordance with the priority of

construction of various pile groups. Sequence of piling shall be decided by the consultant.

37 | P a g e

Pile Cap:

A pile cap is a thick concrete mat that rests on concrete piles that have been driven into soft

or unstable ground to provide a suitable stable foundation. Load from the column gets

transferred to the pile cap. These pile caps can group one or more pile together. The pile

should project 50 mm into the cap concrete.

Finishing of Pile Heads:

Top level of concrete in the pile shall be brought up sufficiently above cut-off level

to allow for slumping or withdrawal of casing tube and also to have a minimum allowance

above cut-off level for removal of all laitance and weak concrete at top level. Any

38 | P a g e

defective concrete at the head of completed pile shall be chipped off and made good with

new concrete bond with old concrete.

During chipping of the pile top manual chipping may be permitted after three days

of pile casting; pneumatic tools for chipping shall not be used before seven days after pile

casting.

Consumption of Concrete in Piling:

After completion, actual quantity of concrete shall be compared with the average

obtained from observations actually made in the case of few piles initially cast. The actual

quantity of concrete may also be worked out based on actual consumption of cement duly

certified by the Consultant. If the actual quantity is found to be considerably less, special

investigations shall be conducted and appropriate measures taken.

Defective Pile: In case, defective piles are formed, they shall be removed or left in place

whichever is convenient without affecting performance of the adjacent piles or the cap as a

whole. Additional piles shall be provided to replace them as directed.

Any deviation from the designed location alignment or load capacity of any pile

shall be noted and adequate measures taken well before the concreting of the pile cap and

plinth beam if the deviations are beyond the permissible limit.

BASIC PROPERTIES OF DRILLING MUD (BENTONITE):

Properties:

39 | P a g e

The bentonite suspension used in bore holes is basically clay of Montmorillonite

group having exchangeable sodium cations. Because of the presence of sodium cations,

bentonite on dispersion will break down into small plate like particles having a negative

charge on the surfaces and positive charge on the edges. When the dispersion is left to

stand undisturbed, the particles become oriented building up a mechanical structure at its

own.

This mechanical structure held by electrical bonds is observable as a jellylike mass

or jelly material. When the jelly is agitated, the weak electrical bonds are broken and the

dispersion becomes fluid.

Functions:

The action of bentonite in stabilizing the sides of bore holes is primarily due to the

“Thixotropic property” of bentonite suspension. The thixotropic property of bentonite

suspension permits the material to have the consistency of a fluid when introduced into the

excavation and when undisturbed forms a jelly which when agitated become fluid again.

In the case of a granular soil, the bentonite suspension penetrates into the sides under

positive pressure and after a while forms a jelly.

The bentonite suspension gets deposited on the sides of the hole and makes the

surface impervious and imparts a plastering effect. In impervious clay, the bentonite does

not penetrate into the soil, but deposits only a thin film on the surface of the hole. Under

such condition, stability is derived from the hydrostatic head of the suspension.

40 | P a g e

41 | P a g e

Specification:

The bentonite suspension used for piling work shall satisfy the following requirements:

The liquid limit of bentonite when tested in accordance with IS: 2720(Part V)-1965

shall be more than 300 percent and less than 450 percent.

The sand content of the bentonite powder shall not be greater than 7 percent. The

purpose of limiting the sand content is mainly to control and

reduce the wear and tear of the pumping equipment.

Bentonite solution should be made by mixing it with fresh water using pump for

circulation. The density of the bentonite solution should be about 1.12.

The Marsh viscosity when tested by a Marsh cone should be about 37 seconds.

The swelling index as measured by the swelled volume after 12 hours in abundant

quantity of water shall be at least 2 times its dry volume.

The pH value of the bentonite suspension shall be less than 11.5.

PILE LOAD TEST

Pile load test is the most direct method for determining the safe

loads on piles including its structural capacity with respect to soil in

42 | P a g e

which it is installed. It is considered more reliable on account of its being

in-situ test than the capacities computed by other methods, such as

static formula, dynamic formulae and penetration test data.

Scope:

a) Vertical load test (compression),

b) Lateral load test, and

c) Pull-out test.

Types of tests:

There are two types of tests for each type of loading (i.e., vertical,

lateral and pullout).

Initial Test:

This test is required for one or more of the following purposes. This

is done in case of important and/or major projects and number of tests

may be one or more depending upon the number of piles required.

Determination of ultimate load capacities and arrival at safe load

by application of factor of safety,

To provide guidelines for setting up the limits of acceptance for

routine tests,

To study the effect of piling on adjacent existing structures and

take decision for the suitability of type of piles to be used,

To get an idea of suitability of piling system, and

To have a check on calculated load by dynamic or static

approaches.

43 | P a g e

Routine Test:

This test is required for one or more of the following purposes. The

number of tests may generally be one-half percent of the total number

of piles required. The number of the test may be increased up to 2

percent in a particular case depending upon nature, type of structure

and strata condition:

One of the criteria is to determine the safe load of the pile;

Checking safe load and extent of safety for the specific functional

requirement of the pile at working load; and

Detection of any unusual performance contrary to the findings of

the initial test, if carried out.

Routine load tests on piles:

Routine load tests shall be carried out on selected piles after 28 days

of concreting in accordance with the specification and relative IS codes.

Procedure for Routine Vertical Load Test (Kentledge Method):

1. Excavation for the pile pit shall be done up to cut-off level with

keeping sufficient working area around the pile.

2. Pile to be tested shall be chipped off and dressed to natural horizontal

plane till sound concrete is met or up to cut-off level which is higher.

3. Top of pile shall be made level with sand or cement mortar.

4. Bearing plates of required thickness & size shall be placed on pile

head with centre coinciding the pile centre.

44 | P a g e

5. Hydraulic jack of required capacity will be placed centrally on the

bearing plates of required thickness & size on the top of jack.

6. Main girders of required section (depend on the load test) shall be

placed on the test pile over jacks and bearing plates.

7. Both ends of main girder shall be placed on temporary supports,

made up of filled gunny bags or PCC. Main girder shall be placed level

& centre coinciding with the centre of the test pile.

8. Supports for secondary girders shall be made with filled gunny bags

at equal distance from the test pile centre according to size of

platform required, as per design. The height of support shall be

sufficient (min. 3-4” from the top of bearing plates to bottom

secondary girders) to allow bending of secondary girders due to

Kentledge.

9. Secondary girders of required section shall be placed cross & over the

main girder.

10.Kentledge consisting MS Billets/Blooms (3.7 MT wt.) shall be placed

symmetrically on top of platform as per requirement of Test load and

design.

11.Datum bars parallel to Main Girder, rested on fixed supports shall be

at a distance of 3D(subjected to a min. of 1.5m) from the centre of

pile on both sides, where D is diameter of pile.

12.Four numbers of Dial Gauges of 0.01mm sensitivity to measure the

settlement of the pile shall be fixed with datum bars and needle of

45 | P a g e

gauge touching to the bearing plate placed on the top of pile. Small

glass piece shall below needle of dial gauge to get smooth surface.

13.After completion of all above arrangements, hydraulic lines shall be

connected to the jack and hydraulic pump attached with calibrated

pressure gauge to note the pressure at each stage of loading &

unloading.

46 | P a g e

14.Loading on the test pile shall be commenced on the following manner:

The test shall be carried out by applying load in stages, each

increment being 20% of safe load on the test pile (exact

increment of load depends on the ram diameter of the jack &

least count of Pressure gauge).

For each stage of loading, the load shall be maintained till rate

of displacement of pile top is either 0.1mm in first 30 minutes or

0.2 mm in first one hour or till 2 hours whichever occurs first.

The pile settlement shall be noted at each stage of loading.

The full test load shall be maintained 24 hours and settlement

shall be measured at every one hour interval.

15.Unloading of test load shall be started after 24 hours of observation.

Unloading shall be done in same stages and rebound shall be

measured at each stage of unloading.

Recording of data:

47 | P a g e

Complete records of boring and concreting process for each pile shall be

maintained:

1. Details of test:

Pile number and location.

Existing ground level, cut-off level and top of level of casting.

Nominal shaft and inside diameter of casing.

Date and time of start of boring.

Length of casing driven and depths bored vs. time.

Description and thickness of various strata encountered.

Details of any obstructions encountered (depth from existing ground

level, thickness and time taken to penetrate through the same).

Rock levels and time rate of boring through rock strata.

Final depth of boring (foundation level).

Standard penetration test at bottom of hole, if any.

Date and time of completion of boring.

Date and time of start and completion of flushing of borehole with

fresh bentonite fluid before concreting.

Time of lowering reinforcement cage and tremie pipes with total

lengths.

Date and time off start of concreting.

Nos. of mixes poured. Level of concrete inside the borehole and

length of tremie pipes at various stages of concreting.

48 | P a g e

Concrete grade, mix proportion, water-cement ratio and slump test

results.

Empty boring length and concreted length below cut-off level.

Results of tests on bentonite slurry used.

2. Details of instruments used:

Specification of jack, pressure gauge and dial gauge.

Capacity of jack and Calibration of pressure and dial gauges.

Design load, description of location and identification marks of pile

for testing.

2. Test records: Records of settlement and rebound shall be entered

as per the proforma.

Procedure for Routine Lateral Load Test:

At the test level a concrete block shall be placed abutting against

the side of the excavation surrounding the pile allowing necessary gap

between the pile head and the concrete block to fit the hydraulic jack in

between. The hydraulic then shall be inserted in between the pile head

and the concrete block to apply lateral load at test level against passive

resistance of soil and weight of concrete block. Thrust blocks shall be

inserted on either end of jack to make up for gap.

Lateral deflection of the pile shall be measured at test level by

means of dial gauges fixed on immovable supports. The loading shall be

49 | P a g e

applied in increments of about 20% of estimated safe load. Next

increment of load shall not be applied before deflection under a

particular load reduces to 0.02mm per hour. A load deformation curve

shall be plotted. The displacement shall be read by using atleast two

dial gauges of 0.01mm sensitivity spaced at 300mm apart and

interpolated at load point from similar triangles.

Assessment of Safe Lateral Loads:

The safe lateral load shall be least of the following:

Fifty percent of the final load at which the total horizontal

displacement increases to 12mm at test level.

Load at which total horizontal displacement corresponds to 5mm at

the test level

50 | P a g e

Pull-Out Tests:

Pull-out load test on pile shall be conducted at proper locations and

levels. For this purpose, a test pit shall be excavated by an open

excavation through all types of soil upon the required depth and size.

The base of such a pit shall be of min. 3m x 3m size with adequate side

slopes with provisions for shoring and dewatering. The excavated

materials shall be dumped sufficiently away from the edge of excavation

so as not to endanger the stability of pit. The pit shall have adequate

side slopes with provision of shoring and dewatering. After completion of

the test, the pit shall be backfilled and compacted in layers.

Pull-out load test Set-up:

Uplift force shall be applied by means of hydraulic jacks fitted with

gauges using suitable pull out setup consisting of a structural framework

resting on two immovable supports. The jacks react against a frame

attached to the top of the pile such that, when the jacks are operated,

the pile gets pulled up and the reaction is transferred to the two

supports which are at 2.5D away from test pile edge (where D is the dia.

of pile).

The framework can be attached to the pile top with the

reinforcement bars, which may be threaded or to which threaded bolts

may be welded.

51 | P a g e

Pull-out load shall be applied in a series of vertical upward incremental

load, each increment being 20% of the estimated safe pull-out load

capacity or 1t whichever is less. Upward movement of pile shall be

recorded with three dial gauges of min. 0.1mm sensitivity and held by

datum bars resting on immovable supports.

Assessment of Safe Loads:

The safe pull-out load shall be taken as the least of the following:

Two-thirds of the load at which the total displacement is 12mm.

Half of the load at which the load displacement curve shows a clear

break.

52 | P a g e

Integrity Testing on Piles:

Purpose:

In addition to the static load tests to be carried out as specified in the

foregoing integrity testing of piles also known as low-strain testing shall

be conducted on a number of selected piles to detect any pile defects,

and pile health parameters like voids, cracks, soil inclusions, necking

and diameter changes. To determine Integrity of pile in its total length and the

unknown length of pile in existing structures

Pile preparation for the test: The pile head must be clean,

accessible, sound and free from standing water. The test shall be

conducted on a pile which has been cast at least 7 days before.

Equipment for testing: The tests shall be performed with a small

impact device (a small 6 pound spring loaded nylon tipped hand held

hammer), sensitive accelerometer, special purpose, PIT collector and an

output device like a plotter or graphics printer which shall be provided

by the Consultant for carrying out the least at site.

Method of Testing: The accelerometer will be attached to the pile top

using a viscous material. Low strain compressive impact waves will be

generated by tapping the pile with the top of the hammer. When the

downward travelling compression wave encounters a change in cross-

section or in concrete quality, it generates an upward travelling tension

wave which later is observed at the pile top. The low strain compressive

impact wave and its reflections will be sensed by the accelerometer.

53 | P a g e

The signal will be converted into a velocity measurement, presented on

a screen as a function of time and stored. The velocity records along

subsequent reflections rom either the pile top or from pile

discontinuities shall be graphically displayed, output directly to a plotter

or/and transferred to a disk.

Interpretation of test Results and Reporting:

Analysis to be submitted shall be carried by exponential

amplification of the signal with the time and the average velocity curve

obtained by numerically integrating the acceleration record.

The test and its interpretation shall be conducted by specialized

agency or persons specially equipped and trained for the purpose by the

manufacturer of the testing equipment.

54 | P a g e

CONCLUSION

55 | P a g e

CONCLUSION

The piling and civil works for expansion of Rolling Mills, RINL VSP were

observed. It was learnt that the soil investigation was initially conducted by taking bore log

samples and further analyzing for the safe bearing capacity of the soil across the mill. After

the design data and drawings were obtained, the construction commenced at the site.

Initially pile boring was conducted using rotary pile driving rigs. The sides of the borehole

are stiffened by pumping bentonite slurry. After flushing the bentonite slurry the

reinforcement cage was lowered and subsequently followed by casting concrete. Later on

the dead concrete of about 750mm above the cut-off level was chapped and the bars are

bent for casting the pile cap. Before the construction of pile caps, pile tests are conducted

on a number of piles. If there is any defective pile, an additional pile is constructed beside

it based on the design. Subsequent structures like pile cap, pedestal and walls were

constructed.

All necessary safety and quality stipulations are ensured at the site for better

working at site.

56 | P a g e

BIBLOGRAPHY

57 | P a g e

BIBLOGRAPHY

IS 2911 : Part 1 : Sec 2 Bored cast-in-situ piles

IS 2911 : Part 4 : 1985 Load test on piles

IS 456 : 2000 Code of practice for RC Structure

58 | P a g e