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[k.gangadharan]

Sub: Pile testing in tall buildings.
My question is addressed to Er. Jaydeep Wagh and Er. J Shukla.

For tall buildings with 100 storeys and above, the pile loads are huge and therefore large dia piles are used . To site an example: for Burj Khalifa Tower, Structural Designer OF SOM , William Baker has stated that 1500. mm dia. piles were cast to a depth of 40.0m resting on dense sand
and the design load per pile was 3000. metric tons. These piles were tested with 6000 tons load, twice the design load. How to do the testing with such enormous load and what method was used for testing?
Are they testing with kentle edge loading using powerful hydraulic jacks? Any idea
about the type of loading method used ?
Now there is another method of testing pilkes using 'Dynamic cum integrity testing' of piles. This is an impact type of testing the piles.
Two companies 'CONSTRUCTION DYNAMICS' owned by Mr. Pushkar Deshpande Of Mumbai and another company 'GEODYNAMICS' run by Er. Ravi Kiran Vaidya of Baroda are doing these tests. They are using a software developed in US, for testing the piles. They are doing pile testing works using this method in India and in middle east countries. They are working under the advice of DR. Narayanan Naik of Mumbai, Geo technical Engineer and author and adviser of foundations for buildings.
Can we use these Dynamic cum integrity testing of piles for such huge loads coming under tall buildings?
KIndly express your remarks on this.

regards

K. Gangadharan
structural consultant
Trivandrum

[gautam chattopadhyay]

6000 MT cam be achieved if the cantileges be of steel or such material heavier then concrete. One 1 m cube of concrete will weigh 2.4 MT requiring 2500 such cubes to be placed. While steel boxes filled up with boulders or dry sand weighing 10 or 20 MT each will need less number of boxes.

One investigator from Calcutta, Mr. Shyamal Mitra once told me of his concept of indirect loading on pile by jacking up a beam that will exert downward load on pile. However, the precision needed for that type of work mmay not be maintained at field.�

下午坐,12月1日,2012年在利比亚,k.gangadharan forum@www.buonovino.com)> wrote:

[Sorabh.Gupta]

Dear Er. Gangadharan,


Although your question has been addressed to the forum seniors, I am going to attempt a first draft response.

Several pile load test methods are available these days, some of which are:

1. Static Pile Load Test- This is the most common form of load testing of piles, and may be carried out either by use of kentledge method, or by the use of reaction piles (as mentioned by Mr. Chattopadhyay in his post). However, as pointed out by you, static load testing becomes quite cumbersome (and expensive!) when one is dealing with high-capacity foundations.
   
2. Use ofOsterberg Cells(or, more generally,Biaxial Static Load Testing) in conjunction with instrumented piles, is gaining popularity in the US, Europe and the Middle East. This is a powerful method, in which the hydraulic jack assembly is actually installed within the pile, and the load (equal and opposite!) is applied on the pile segments. Naturally, this reduces the maximum test load to be applied (since only a portion of the pile needs to be mobilized) for the static test. However, the interpretations of the test result are fairly mathematical, due to which opinion on this test method is divided. Further, experience in India is limited so far.
   
3. High Strain Dynamic Pile Load Testing(or HSDPLT) is another method which is gaining a lot of popularity in India, especially with the growing constraints in testing time and cost. The method involves dropping a small weight (typically 1-2% of the test load) on the top of the pile from about 0.5-1.5m height, and monitoring the force and velocity at the pile top using strain transducers and strain gauges affixed to the top of the pile. Once set up, this test takes only about30 minutes per pileto carry out, and can basically simulate the static load-displacement curve. This test method is based on well-established wave equations, and can give extremely reliable results. However, in my opinion, a combination of static and dynamic load tests should always be carried out at any project site so that the results may be correlated.
   
   I have used this method myself on several projects now to test piles to more than 1500 MT test load, with good success. In fact, there are quite a few agencies in the country (including us at Cengrs Geotechnica Pvt. Ltd., New Delhi) which now have the PDA equipment (manufactured by Pile Dynamics, Inc., USA) required for dynamic testing.
   
   [Note of caution here- this method is only as good as the engineer performing the test, since it requires a good understanding of geotechnical engineering and dynamic pile behavior. An "L1" style of contract award for specialized testing often leads to hazardous results!]

To wrap up, I would like to point out that simply 'load-testing' piles / foundations on sites is not enough. The testing agency must be capable of analyzing the load test results, comparing them with the available geotechnical data, pour card data, integrity test data (PIT, CHUM, etc.), and coming up with logical conclusions on the expected vs. actual foundation performance. An intelligent QC program can help the design team maximize foundation performance and / or prevent disasters and delays owing to foundation distress or failure.

Regards,
Sorabh

p.s. I have uploaded a recent presentation on this topic for those who might be interested-https://docs.google.com/folder/d/0B_lQn2s7qixiakcyWllCcXVDams/edit

[Senthil_Nath_GT]

Dear Mr. Gangadharan,


To touch upon�Osterberg Cell�test, as mentioned by Mr. Gupta,�Osterberg Cell (O-Cell) tests are widely used in middle east and west. Infact, O-Cell testing have completely replaced the kentledge loading system of large diameter bored piles in the US because of kentledge cost and safety.�

简而言之,O-Cell液压��是杰克的device which is�installed in the pile itself during construction and loads are applied from within the pile after concrete sets.This testing does not require any kentledge load or any other external reaction frame and is mainly used for high test loads (>5000 Ton)/ Rock socketed piles/overwater and battered piles. It is also possible to�separate Shear and Bearing components from the arrived capacity.�However, O-Cell testing requires planning during installation stage and may not be suitable for sheet piles.


O-Cell testing have been conducted in India for project like�Bandra�Worli Sea Link, Mumbai; World One Towers, Mumbai and few high rise buildings in Delhi-NCR region.


乔博士O-Cell专利产品(专利j Osterberg), there are limited contractor providing such service. Often, overseas contractors are engaged for such service and hence it becomes justifiable (cost wise), only for big projects involving either lots of test or very huge loads.


Regards,
Senthil Nath
Geotechnical Engineer



On Tue, Dec 4, 2012 at 11:43 AM, Sorabh.Gupta forum@www.buonovino.com)> wrote:

[cckeshav]

Dear SEFIans:

The Osterber Cell tests are popular but they are limited to cases wherein skin friction is considered in the design. The test fails if skin friction is not mobilized. In many cases, particularly with rocks at shallow depths, this method can not be used.

C.Channakeshava


Subject: [E-CONF] Re: tall building design- pile load testing
From:forum@www.buonovino.com
Date: Tue, 4 Dec 2012 16:13:30 +0530
To:econf34289@www.buonovino.com

Dear Mr. Gangadharan,


To touch upon Osterberg Cell test, as mentioned by Mr. Gupta, Osterberg Cell (O-Cell) tests are widely used in middle east and west. Infact, O-Cell testing have completely replaced the kentledge loading system of large diameter bored piles in the US because of kentledge cost and safety.

In simple terms, O-Cell is hydraulic jack kind of device which is installed in the pile itself during construction and loads are applied from within the pile after concrete sets.This testing does not require any kentledge load or any other external reaction frame and is mainly used for high test loads (>5000 Ton)/ Rock socketed piles/overwater and battered piles. It is also possible to separate Shear and Bearing components from the arrived capacity. However, O-Cell testing requires planning during installation stage and may not be suitable for sheet piles.


O-Cell testing have been conducted in India for project like Bandra�Worli Sea Link, Mumbai; World One Towers, Mumbai and few high rise buildings in Delhi-NCR region.


乔博士O-Cell专利产品(专利j Osterberg), there are limited contractor providing such service. Often, overseas contractors are engaged for such service and hence it becomes justifiable (cost wise), only for big projects involving either lots of test or very huge loads.


Regards,
Senthil Nath
Geotechnical Engineer



On Tue, Dec 4, 2012 at 11:43 AM, Sorabh.Guptaforum@www.buonovino.com)> wrote:
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