Driven concrete filled pipe piles

[ShaktiSingh]

I am working on the construction of a boat house in lake
The edge of the boat house is 25 ft away from the edge of water. The max depth of water is 5 ft
The structural has recommended the construction of driven closed ended pipe piles with a diameter ranging from 6 in to 12 in, to be filled with concrete.
Can someone please provide me with a link or a reference, a design example or manual or text dealing with the above subject.

Thank you

 

[JedClampett]

There are many refererence books on driven piles. Any good Geotechnical Textbook will have information on them.
If you're looking for something more specific to your situation (piles driven in a lake), I can't help you.

 

[jdonville]

ShaktiSingh,

What has the geotechnical engineer recommended?!

Jeff

 

[ShaktiSingh]

For some reason we are waiting for the Structural to make the call on the type of foundation ( I think it is due to ecomonics). Once he decides what he wants, we the geotechs need to design the recommended foundation.

I believe that the pipe piles will be closed end while driving into the ground and will be later filled with concrete ( which I believe will greatly increase the tip capacity).

 

[gman11]

Filling the pile won't increase the tip capacity. If anything the capacity will be lower because you are adding the weight of the concrete as a load. A closed end pile is just that closed at the driving end.

 

[gman11]

http://www.fhwa.dot.gov/engineering/geotech/library_listing.cfm

If you go to this site you can probably find a manual on what you're dealing with to download. I think I even saw some free public domain software on the site. I'm one of the authors on the Manual for Design and Construction Monitoring of Soil Nail Walls

 

[BigH]

It is not mentioned as to the nature of the subsurface soils through which the pile would be driven. Closed-ended tube piles have been quite common (and almost exclusively used in my experience in Ontario, Michigan and other places) - they are not a "unique" type of pile. They are, however, displacement piles. As such, they are especially good when driving into sandy soils. They drive rather readily through soft to firm clays - but we would end up driving them to and slightly into glacial till. (sometimes we would have to pre-drill if driven through a significant layer of clay in order to ensure verticality.) As displacement piles filled with concrete, they would basically take up the same weight as the material through whcih the pile was driven. For practical purposes, I would think this is not worth a worry - unless, of course, you have a lot of the pile sticking out of the water.

 

[geodan]

gman11 is correct in that filling the pile will not increase the tip capacity. Do you have soil borings and subsurface soil information? Soil type, strenght, properties? Are you looking at an end-bearing pile?

Deep foundations can get very complicated. Different types of piers also have different methods and different ultimate bearing capacities.

I would personally recommend using Meyerhof's method for calculating Qp (assuming a firm strata exists) as his method is a good 'middle of the road' or average approach and is generally conservative.

However, for estimating Qp for construction purposes (needed to overcome for driving), I would recommend using Vesic's Method - based on the theory of expansion of cavities. It is generally considered to be more accurate (though not as conservative).

Though if no firm strata exists, then it is likely that Qtip will only contribute <20% of the ultimate resistance as most will be derived from skin friction.