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Saikiran Gone

cohesive soil
Pile Foundation Design (Cohesive Soil)

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Dear Engineers,

 

Please guide me to find adhesion factor (alpha)  value in the calculation of pile capacity in cohesive soil as  per Eurocode 7 - DA3. In all worked examples, they were showing value as alpha = 0.4, I am in confusion that, is this value is constant or varies. If it varies how to find for different values of cohesion (Cu).

 

qsk = alpha * Cu. (Basic Formula).

 

Please find the one of the PDF I referred for worked examples, The above query can observe on page 28/37.

 

http://eurocodes.jrc.ec.europa.eu/doc/2013_06_WS_GEO/presentations/08weUP-Orr-Worked-examples-design-of-pile-foundations.pdf

 

Thanks,

Regards,

Saikiran Gone.

 

 

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Hallo.

 

Eurocode has two methods for design of axially loaded piles (EN 1997-2 annex D.6 and D.7). These will not provide you directly with the adhesion factor alpha you're looking for, but may help you with the design.

 

If you want to find the adhesion factor alpha refer to good literature for pile design. For now, I can tell you only that the factor does vary, usually from 0,25 upward, but it depends on many things, so again, refer to good literature. You may start with books from Tomlinson.

 

Cheers

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Thanks,

 

Reinisgailitis, Can you please clarify the below query.

 

Dear Sir, 

What is the force value to be taken for horizontal deflection of the plie foundation 

As per boorms method from Tomilson textbook, What H value to be taken for deflection calculation. 

Please find the attached images for your ready reference. 


Query: H value is the direct lateral force or moment also included. Please clarify. 
H = lateral force or 
H = Lateral force + Moment/eccentricity. 


http://www.sefindia.org/forum/viewtopic.php?p=76624#76624

Regards, 
Saikiran Gone.
 

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The force you're interested in getting the deflections for. Yes, if the moments is applied to the individual pile you should take it as the H=moment/eccentricity + usual H. If you need to know deflection under ULS loads you use those loads, if you need to know under characteristic combination then you take those. 

 

P.S. Broms method is an estimate, far from the most reliable/precise, so be aware. 

 

Cheers

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On 5/10/2017 at 10:22 AM, ReinisGailitis said:

The force you're interested in getting the deflections for. Yes, if the moments is applied to the individual pile you should take it as the H=moment/eccentricity + usual H. If you need to know deflection under ULS loads you use those loads, if you need to know under characteristic combination then you take those. 

 

P.S. Broms method is an estimate, far from the most reliable/precise, so be aware. 

 

Cheers

 

Hi Reinisgailitis , Thanks for your info. Can please suggest which book/material to refer for deflection calculation of pile foundation.

 

Regards,

Saikiran Gone.

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On 5/15/2017 at 5:21 PM, Saikiran Gone said:

Hi Reinisgailitis , Thanks for your info. Can please suggest which book/material to refer for deflection calculation of pile foundation.

 

Regards,

Saikiran Gone.

 

Check out the book: "Single Piles and Pile Groups Under Lateral Loading".

 

I haven't used it myself but from what I understand the best method for practical design of laterally loaded piles using spreadsheet etc is "p-y" method in the book mentioned above (it is called the same in many other books as well).

 

Best of luck,

Reinis

 

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