foundation system of burj al arab

WHAT IS DAMAGED PILES?

A heavily loaded structure supported on soil which does not render adequate bearing capacity and where continuous foundation like mat is not suitable cast-in-situ pile used. In this process bore hole are formed by suitable devices and concrete is poured around a reinforcing steel case. Due to some difficulties and some mistakes during piling some piles are considered as damaged pile. Bored piles are considered damaged when,


- The 28 days ultimate strength of concrete from the test specimens are below 27.6 MPa

- The concrete specimens cored from the finished piles show strengths below 27.6 MPa at 28 days, and the Engineer considered it defective.

- The length of bored piles do not met the requirements of the drawings or contract documents.

- The requirements according to codes listed below are not satisfied.
SI.
Requirements
Codes
1
Welding of reinforcing steel
AS/NZS 1554.3:2008
2
Concrete Structures Standard
NZS 3101 Parts 1 & 2:2006
3
Specification for concrete production
NZS 3104:2003
4
Methods of test for water and aggregate for concrete
NZS 3111:1986
5
Methods of test for concrete
NZS 3112:
6
Specification for water and aggregate for concrete
NZS 3121:1986
7
Steel reinforcing materials
AS/NZS 4671:2001
8
Design and Construction of Drilled Piers.
ACI 336.3R
9
Recommendations for Design, Manufacture, and
Installation of Concrete Piles.
ACI 543R
10
Standard Test Method for Individual Piles Under Static Axial Tensile Load.
ASTM D3689
11
Standard Test Method for Piles Under Lateral Loads.
ASTM D3966
12
Structural Welding Code-Reinforcing Steel.
AWS D1.4

- Tests show that bored pile cannot withstand the test loading equivalent to 2.5 times the design safe load because of defective piles which could have been resulted from collapsing of bored hole, impurities mixed into the concrete, bored holes being smaller than the specified sizes, inconsistent concrete strengths, and segregation of concrete mixture. In any case, the Contractor must be responsible for all payments to repair, or re-construct new pile as directed by the Engineer. Furthermore, the Contractor must be responsible for any additional expenses in making a necessary corrective actions to the entire structure such as expenses for "Tied Beams", "Micro Piles", "Enlargement of the Footing". In addition, the expenses involve in coring bored pile for concrete specimens, laboratory tests of the specimens, filling the core holes, and other bored piles repair shall be the responsibility of the Contractor if such actions are for confirmation purposes.

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