Piles fail lateral load test

[StructuralEngGuy]

Hello all,

I have a project with 30' deep piles currently in construction. The contractor has driven test piles and is testing them for lateral load capacity in accordance with ASTM D3966. He has indicated that the piles are failing the required capacity miserably. I am having him test another pile, but if the results are similar, what can be done? By the way, the lateral load capacity was determined by the geotechnical engineer during design.

 

[PEinc]

Some options may include:
Drive more piles
Drive wider piles
Add battered piles
Improve the soil around the upper section of the piles
Use the pile cap to resist lateral movement
Ask the geotech

http://www.PeirceEngineering.com

 

[Ron]

Agree with PEinc...would probably opt for battered piles with redesigned cap

 

[VoyageofDiscovery]

Just curious, what sort of load capacity were you expecting?

 

[StructuralEngGuy]

Thanks. I was thinking battered piles as well. The geotech report noted the lateral capacity would be 40 tons at 1" deflection. The tested pile is deflecting 1" at just 16 tons. The geotech is going out to the site today to see what he can do.

 

[emmgjld]

Wow, 40 tons is a lot.
I would wonder if the encountered soils/rock are as expected.

 

[FixedEarth]

Some reports give "ultimate" lateral capacity & ask the designer to apply a factor of safety. I am wondering if that was the case here?

 

[VoyageofDiscovery]

If its an H-Pile, 40 ton is unrealistic. Thus it is what it is! The geotech should file that one under experience!

 

[jgailla]

I would think that the lateral pile, assuming everything was done right, would fail at the "ultimate" capacity, not the service capacity. It's been a while, but we would vertically load test piles to double the service load.

 

[fattdad]

If somebody says 40 tons at 1-in deflection there is no safety factor involved. The implication is that they actually calculated 80 tons for 1-in and used a safety factor of 2? The implication is that they calculated 40 tons at 1-in but really think you should consider 20 tons for 1-in? Alternatly, they could have applied a safety factor in their P-Y analysis, based on data uncertainty.

A fixed head pile cap would help.

The geotechnical engineer should be in a position to provide more insight, providing that the "geotechnical engineer" is really a geotechnical engineer.

f-d

¡papá gordo ain’t no madre flaca!

 

[ishvaaag]

Curious that a 16 ton would be a 2.5 safety factor for some 40 ton limit load. As FixedEarth asks to consider.

Then if you need the 40 tons service level and IF the piles are more or less floating it seems a difficul issue, even inclined piles would have some difficulty (but would help) and if not compliant you would have to use very rigid pile/caisson outfits to deeper layer of fixity, an unlikely proposition, hence more inclined piles.

If point bearing, inclined piles as suggested may ber reasonable solution if acceptable from seismic behaviour.

 

[Zambo]

Are the piles being tested at the correct elevation, by that I mean at cut-off level not at existing ground level. The upper soils are generally, although not always, weaker and it could be that lateral capacity improves significantly at lower level.

Just noticed the last post was 5 May - wonder what happened ....