Rapid construction of maintenance free infrastructure on very compressible soil demands new foundation techniques which can be applied economically on large-scale projects. A new system named AuGeo Piling System was developed to construct embankments on piles, whereby a geogrid is used to transfer the weight of the embankment to the pile foundation. With this so-called AuGeo piling system it is possible to construct settlement free embankments within a very short time period.

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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Micropile is another type of pile which is act as a supporting structure to transfer the load from the building to the ground. As the name implies, micropile is small diameter piles constructed by the drilling process and are often keyed into rock. There is various diameter of micropile can be found in the market ranging from 100mm to 250mm. Of late, technological advancement in machinery has made it possible for micropile of much greater diameters to be constructed.

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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Sheet piling produced to this specification is usually manufactured from coils, decoiled and fed through a multi stand (roll) forming mill at ambient temperature. Through innovation and benefits of latest technology, Cold Formed Steel Sheet Piling is formed by continuous flat steel strip rolled into corrugated profile at ambient temperature. The cold working by rolling process could increase the strength of material and good section properties per weight. Nowadays, cold formed steel sheet piling is widely used in the industry for piling foundation.

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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There are several types of pile driving method in the piling construction, type of pile driving method used is depending on the condition of soil and location of the site. However, different piling machine will be used with different pile driving methods too. The specification for pile driving mentioned below is generally recommended for pile driving of prestressed spun concrete piles by using percussion method. Engineers may be required to modify some of the clauses to suit requirements of different site conditions.

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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