Posted by Harry Lee on June 14, 2009 at 12:11 pm
Structural foundation or deep foundation is a type of foundation that is used to transferring the structural loads in to the subsoil. These are several ways of transferring structural loads into the subsoil on sites where ground conditions are unfavourable. The bearing capacity of the subsoil can be increased by ground improvement techniques such as :
- 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
Archived under Bored Pile, Deep Foundation, Retaining Wall
Posted by Harry Lee on June 2, 2009 at 8:54 pm
ICP piles is another type of piling, it’s also known as Pretensioned Spun High Strength Concrete Piles (ICP PHC Piles) which offer an economical foundation system with consistent and superior quality compared to the ordinary concrete piles.
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.
Archived under ICP Pile, Piling
Posted by Harry Lee on May 12, 2009 at 9:16 pm
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.
Archived under AuGeo Piling System, Pile Driving, Piling
Posted by Harry Lee on May 6, 2009 at 11:07 pm
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.
Archived under Micropile, Pile Driving, Piling
Posted by Harry Lee on April 25, 2009 at 12:31 am
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.
Archived under Pile Driving, Piling, Sheet Piling
