• replacement of non-load bearing layers of soil close to the surface.
• soil consolidation using pre-loading or vertical drains.
• soil compaction using grout injection; deep vibration or stone columns.

Alternatively, structural loads can be transferred to stronger competent strata at depth by the use of :

• bored piles
• diaphragm wall elements
• mixed in place (MIP) piles
• piles reinforced by steel bars
• vibrated concrete columns

Technical literature on all these special alternative construction techniques is available on request from foundation contractor. There are several ways to build structural foundation or deep foundation, they are retaining wall and bored piles.

Retaining Wall

Retaining wall is a type of structural foundation or deep foundation, which is used to transfer the structural into the subsoil. The problem of providing stable retaining structures close to existing buildings or of constructing watertight excavation pits can be solved in a number of ways. However, the most appropriate solution is almost always the installation of a bored pile retaining wall.

Bored Piles

In general bored piles offer the most economical foundation as they can be constructed in a wide choice of diameters, typically ranging from 300mm to 1800mm, and to depths of up to 70m at rakes of up to 1:4. They can thus be tailored precisely to the particular requirements of the building or excavation. This flexibility means that bored piles can provide solid foundation elements suitable for almost all site conditions.

* Friction Pile

* End Bearing Pile

Bored piles can be classified into two main groups, according to their load bearing behaviour: friction piles, which transfer loads mainly by frictional resistance along the shaft; and endbearing piles in which load is primarily transferred to the surrounding soil of through the pile base. Depending on the structural requirements, bored piles may be constructed singly, in groups or as walls using secant, contiguous or king piles, with or without infill.

* Single Piles

* Pile Groups

* Vertical And Raked Piles

* Piled Wall

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ICP Piles are circular in cross-section and are manufactured in sizes ranging from diameter 250mm to 1200mm with standard lengths varying from 6m to 46m in single pieces. ICP Piles can be easily joined to any combination of length as per design requirement. ICP piles are manufactured with steel end plates for splicing.

Today, with the state-of-the-art autoclave curing system, ICP Piles can be installed immediately after autoclaving. ICP piles have been used extensively as foundation piles for power stations, highrise buildings, civil engineering works, bridges, marine structures, harbours, schools and government project, etc.

Materials For ICP Piles

1) Aggregates
Coarse aggregates shall be 20mm granite. Fine aggregates shall be clean river sand or washed mining sand.

2) Cement
Ordinary Portland cement.

3) Prestressing Steel
High frequency induction heat treated bars.

4) Spiral wire
Hard drawn wire.

Joint

The joint is designed to have the same performance as the main body particularly in respect of bending strength. All ICP piles will be supplied with steel extension plates for splicing.

Lifting Points

Two lifting point will be marked on all piles exceeding 9m. No special lifting bolt or wire rope is cast into the piles. Lifting is by wrapping wire ropes round the piles at specified points.

Pile Shoes

All ICP Piles will be supplied either open ended, with a flat shoe or with an X-pointed shoe.

Curing

After casting, the piles are steam cured. When the concrete reaches the specified transfer strength, the piles are demoulded, marked and checked for quality. The piles can normally be transported and driven when the cube strength reaches 50 N/mm2. Today with the state-of-the-art autoclave curing system, the piles can be installed immediately after autoclaving.

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The AuGeo piling system is characterized by a relatively light piling system provided with a cap and an enlarged point. The piles are pushed into the soil at short distances by a modified drain stitcher. Compared to a standard ramming method, where it is very important that no rest settlements occur, small settlements will not affect the construction of an AuGeo system or the geogrid mattress.

The AuGeo piling system consists of a corrugated HDPE casing which is filled with a cement mortar. The piles are installed from a working platform. A circular steel tube of dimension 190mm diameter is pushed into the soil by a drain stitcher type MY-200 with a force of approx. 40tons. The tube is closed at the bottom by a 5mm thick steel plate, which acts as an enlarged pile point. This plate remains in the soil. The tube is installed at a regular speed to avoid disturbance of the subsoil and any potential damage to the piles already installed. When the steel tube has reached its final depth, the HDPE tube of diameter 150mm is lowered into the steel casing and filled with a comment mortar. The mortar is mixed on site in a mobile mixing plant and pumped to a temporary storage bin on the installation rig or pumped directly from ready mix trucks. The steel tube is retracted and the pile is cut at its correct level, filled to the top if necessary, and provided with a concrete cap of dimensions 300×300mm. During normal operations, production rate of 20 piles per hour can be achieved.

Areas Of Usage

1) Highways and Railway Embankments

2) Approach Embankments to Bridges

3) Light and medium Industrial Structures

4) Housing Development Area

Advantages Of The AuGeo Piling System

1) Competitive costing. It is cheaper than normal piled embankments.

2) Speed of installation compliments fast track construction projects.

3) Easy to install, no vibrations and very small displacement.

4) Environmentally friendly system.

5) No post construction settlements.

6) Effective load transfer via 2 layers of high strength Geogrid.

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Application of Micropile

In the past micropile was only used when the ground conditions warranted it because of considerations on cost and speed. Micropile is slow because of the drilling and flushing process, it might takes minutes or hours to complete.

But the trend is such, micropile is now gaining greater popularity and getting wider acceptance because of the requirement to comply with no noise and low vibration regulations, expecially in congested environments.

Geotechnically, micropile is most suitable in the following ground conditions :

1) Shallow Bedrock

2) Boulders and Cavities

3) Intermediate Hard Strata

4) Underpinning

How To Install Micropile

Micropile is widely used in the construction field because of the low vibration and no noise, micropile is widely used in housing area, school, hospital or any location which doesn’t allow to make noise while pile driving process. As you know, concrete pile like spun pile and reinforced concrete square pile produce high volume while driving pile. The installation procedure for micropile is almost similar to bored piling, it’s using drilling method.

1) Drilling and Flushing

2) Withdrawing Drilling String

3) Inserting Steel Reinforcement and Grouting

4) Completed Micropile

Construction Photos For Micropile

1) Micropile for underpinning an existing 4-storey office building which showed signs of settlement.

2) The workers are doing micropiling works.

3) Micropiling work in progress. A high pressure compressor is being used for flushing out the drilled materials.

4) A mini, but powerful hydraulic crawler drill which is useful for micropiling works in :
a) Congested locations with extreme headroom constraint.
b) Difficult hillside development where rock is encountered.

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Cold formed steel sheet piling has the similar application as normal sheet pile, the purpose of using cold formed steel sheet piling is same as normal sheet pile too, it’s used to create a working space for the workers to work under ground level. Additional, method of installation for cold formed steel sheet piling should be the same as normal sheet piling as well.

Benefits For Cold Formed Steel Sheet Piling

1) Excellent strength / weight ratio to save construction cost.
2) Precise and proven interlocking system which ease the pile driving and forming continuous straight wall.
3) Flexible production process to offer product the client’s required length, strength and delivery schedule.
4) Roll forming technology guarantee superior surface finishes of sharp and clean contours without die marks.
5) Accurate dimension to meet even tight tolerances.

Applications For Cold Formed Steel Sheet Piling

1) Structural protection for canalization
2) Retaining wall system
3) Effective permeability cut off system or confinement walls at polluted site
4) Waterfront structure for port facilities & jetty
5) Locks and dam
6) Piled foundations
7) Temporary excavations
8 ) Trenches for sewerage and drainage works
9) Bridge abutments
10) Power plants construction
11) Construction of noise barrier

How To Process Cold Formed Steel Sheet Piling

1) Raw material i.e. steel strip is continuously fed in to machine line.

2) Cold formed steel sheet piling is formed by series of designed roller stations.

3) Sheet piling is formed into corrugated profiles to achieve strength and toughness.

4) Precise and consistence shape formed and readily used.

Types Of Cold Formed Steel Sheet Piling

1) OU Section

Advantage of OU Section Cold Formed Steel Sheet Piling :
i) An innovative sections for ease of installation adjacent to building.
ii) Suitably use for canalization work and river bank structural protection.
iii) Effective permeability cut off system.

2) OZ Section
OZ Sections formed continuous corrugation of web where specific location of the interlock symmetrically on both sides of the neutral axis. This will offer type of sections with effective section properties per weight.

Advantage of OZ Section Cold Formed Steel Sheet Piling :
i) An extremely competitive section modulus to mass ratio.
ii) Increased inertia, reducing deflection and allowing high-yield steels to be used for the most economical solution.
iii) Large width resulting in good installation performance.

3) OT Section

Advantage of OT Section Cold Formed Steel Sheet Piling :
i) The combination of great wave depth giving excellent statical properties.
ii) The symmetrical form of the single element has made these sheets particularly convenient for re-use.
iii) Easy fixing of tie rods and swiveling attachments, even under water.

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How To Do Pile Driving With Percussion Method

1) Joints

The bending strength of a joint between two lengths of pile shall be equal or more than the bending strength of the concrete shaft. When two lengths of pile are jointed, the end plates must bear over their complete areas. The two end plates are then welded along their entire periphery with weld size as specified.

1.1 Welding of Joints
All welding shall be carried out in accordance with the requirements of B.S.5135:1974 - Metal-Arc Welding of carbon and carbon-manganese steel.

1.2 Tests for Approval of Welders
Welders shall be qualified in accordance with the requirementsof AWS Code D1.1. Only welders who pass the qualifying tests for the type of weld specified shall be employed on the Works.

1.3 Examination of Welds
Butt welds between the end plates of the joints shall be tested using magnetic particle or dye penetrant test methods. Copies of these test records and reports shall be furnished to the Engineer.

Where such examination reveals defects in the welds, the joints shall either be rejected or repaired. If repeat tests show the weld to be still defective, the joint shall be rejected. The defective weld shall be removed, replaced with a fresh weld and re-examined.

For the purpose of this Clause, cracks, leaks, laminations, lack of complete fusion, undercutting or reduction in wall thickness adjacent to the weld shall constitute a defect.

2) Pile Driving by Using Percussion Method

2.1 Pile Hammers
Shall be of size and type able to deliver consistently an effective dynamic energy suitable to the piles to be driven and the material into which they are to be driven. Hammers shall be provided with proper driving helmets suited for the piles. Any indication of collapse of hoses, tripping of hose lining or any erratic action of the hammer shall be cause for immediate shutdown until the problem has been corrected.

Pile hammers shall be operated at the full rated efficiency and capacity and in the manner specified by the manufacturer, except as directed otherwise by the Engineer, or noted herein below under Reductiono of Hammer Energy.

When a steam or air hammer is used for driving any type of piles, both the volume and pressure of steam or air recommended by the manufacturer of the hammer shall be maintained at all times to ensure full energy of the driving blows. Before pile driving is started, the Piling Contractors shall provide written certification to the Engineer that the pile hammer, compressors and valves have been inspected and found to be in good working condition.

2.2 Reductiono of Hammer Energy
When the pile is set in a pre-jetted or pre-drilled hole or when the point of a prestressed concrete pile is passing through soft soil so that there is little or no resistance to penetration of the pile, there is a possibility that longitudinal tensile stresses may be set up in the pile shaft by the elastic shock waves travelling up and down the pile. For such driving conditions, the length of stroke of the hammer shall be reduced. Failure of the piles due to longitudinal tensile stresses caused by excessive driving shall be the Contractor’s responsibility.

2.3 Pile Cushion Block
The heads of all prestressed concrete cylinder piles shall be protected with a soft wood cushion block at least 15 cm thick to effectively and uniformly distribute hammer blog energy. The block shall be composed of layers of 20mm hi-grade marine plywood or approved equal, and of such dimensions as to completely cover the concrete cross-section of the pile. The cushion block shall be inspected periodically during driving and no driving shall be done with a block that has been unduly worn and compressed with use. Cushion blocks must be replaced when compressed to 1/2 their original thickness, when badly worn or when burning.

2.4 Driving
The piles shall be driven to the driving resistance or tip elevation as determined by the Engineer from pile load tests. The maximum allowable variation at the butt end of the pile shall be 150mm in any direction from the location shown on the Drawings or as directed by the Engineer. Any variation beyond these limits shall be allowed or rejected at the sole discretion of the Engineer.

3) Cutting Off and Capping Piles

Tops of foundation piles shall be embedded in the concrete footing or pile cap for a minimum depth of 75mm (measured at center line of pile). When the top elevation of a pile is below the elevation of the bottom of the cap, the pile shall, if approved by the Engineer be built up from the butt of the pile to the elevatioon of the bottom of the cap by an approved method. The cuts shall be made accurately in clean, straight lines; care shall be exercised to avoid damaging the remaining pile and to ensure full bearing between the footings (or pilecaps) and piles.

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How To Drill Bored Pile

1) Adjust the piling machine on the pile axis and haul with the auger to the drilling place.

2) Start drilling until the auger is filled.

3) Return from the drilling level to the top of the pile hole.

4) Swing to the uploading area.

5) Unload the dirt in the unloading area.

6) Swing back to the top of the hole.

7) Repeat steps 2 to 7 until the pile is completely drilled. Relocated the machine and start steps 1 to 8.

8 ) Start erecting rebar cage using a crane.

9) Use funnel for dry method and tremie for wet method. Start pouring the concrete and finish the pile.

Video On How To Drill Bored Pile

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Normally bored piling has be to carried on those tall buildings or massive industrial complexes, which require foundations which can bear the load of thousands of tons, most probably in unstable or difficult soil conditions. 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 50metres depth of soil. The advantage of bored piling is its’ drilling method, little vibration and lower noise level.

The drilling method is depending on the condition of soil, piling contractor has to do soil investigation and decide which drilling technology has to be carried on. Piling contractor decide the correct drilling technology and minimize disturbance of the surrounding soil. For cohesionless 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 muds such as bentonite suspension. After these, reinforcement bar will be put into the bore hole and concrete will be poured into the bore hole.

Bored piling is popular to be used in construction as a foundation especially for bridge work and tall building as well. Bored piling work has to be done by specialist bored piling contractor, normal piling contractor can’t be done without experience and knowledge about bored piles.

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Procedure and Sketch of How To Produce Super Strength Pile (SS Pile)

1) PC Bar Cutting and Heading

2) Cage Forming

3) Joints Setting

4) Concrete Placing

5) Concrete Batching

6) Prestressing

7) Spinning

Steam Curing

9) Demoulding

10) Autoclaving

These are all the steps of how to produce a SS Pile. All the procedures must be followed exactly and done it clean and neat. Safety protection must be carried on for workers who involved in the process of producing SS Pile. After the SS Pile has been done, it will be handled and stored in the factory or yard and ready for delivery.

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Procedures Of Handling and Storing Piles

1) Two point lifting position to be pitched at 0.2 x L distance from the pile ends (Diagram 1a as above). Alternatively, lifting from the pile ends is to be executed with the following controls :-

i) No jerking movements by the crane.

ii) Crane must be stationary.

iii) Vertical lifting rate at slower pace.

iv) Boom of crane to be swung at minimum rate of movement.

v) Piles are to be carried one at a time.

vi) Wire ropes are to be capable of carrying the load.

vii) Free rotation of the top swivel is to be ensured (Diagram 2 as above).

viii) Wire ropes are to be inclined at least 45 degree acute angle with the pile body. (Diagram 2 as above)

ix) Only PPDC verified / authorized hooks are to be used.

x) Two flat M.S. plate hooks are to be used at cross fin shoe ends or circular / torus hooks for conical shoe ends.

xi) Stoppers are to be put at both sides of the piles and fastened to be ground. (Diagram 1b as above)

2) Lifting from one end for pitching is at 0.2 x L. Pile is to be fastened in such a way to prevent slipping (multiple loop grip tie) with the following controls :-

i) No dragging along ground.

ii) Lifting rate at slower pace.

iii) Lifting piles from the ground is to be done at the open-ends with “C” hook.

iv) Nothing must be below the pile at transfer.

3) Refer to diagram 1a and 1b above for storage details.

i) Piles are preferably to be stored according to their respective lengths.

ii) Spacers of 2″ x 4″ hardwoods are to be placed at 0.2 x L from both ends of the piles and in between the 2 layers of piles.

iii) Preferably the ground is levelled and compacted with a 100mm thick bed of 20mm aggregates.

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