Min Pile Embed for building over water
Min Pile Embed for building over water
(OP)
I have a client that drove about 50 10" diameter piles along their water front property and now want to build a two story boathouse on it. They were driven 6-8' into the soil with a 4500lb drop hammer. They stick above the soil about 15 feet, than there is a dock and above the dock is a two story structure. The contractor hired a PE that is telling them the piles are fine and we can put this building on them. How can he know that if he doesn't know what type of soil or anything about the installation readings (there were none). I've recommended doing exploratory work to determine our soils. I'm being treated like I'm crazy and an overly conservative engineer. This structure will cost $400,000 and have large doors that must remain operable, excessive deflection will make them inoperable. I'm a structural guy and haven't done piles since college. We have 3kip horizontal loads and 34 kips axial loads on some piles. Am I crazy?





RE: Min Pile Embed for building over water
At the least, require a load test on the piles.
RE: Min Pile Embed for building over water
It is possible the that the Contractor's PE has experience on other similar projects in the area... but an educated guess is not worth the risk on this project.
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RE: Min Pile Embed for building over water
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RE: Min Pile Embed for building over water
However, I can imagine the difficulty of running a load test. It might be cheaper to bring in another rig and tap a few and calculate from that the probable capacities.
As with many posts on this web site there could be more information provided so the complete picture is presented. For instance how high a drop for the weight and about what penetration per blow so the ENR formula (or other) could be applied. Also what is the history of work along the area? Are there other jobs of similar nature and what has been their history of problems if any? The contractor may have a good bunch of successful experience. Don't knock his methods until you know more about them. While he may not be an engineer, I am many times impressed about the practical know-how of some contractors.
Also for the structure, can the piles be secured by some moment resisting connections? Give enough overall upper end rigidity, embedment may not be of concern.
Finally, describe the PE's statement or report that all is OK. Maybe he went through all this already.
RE: Min Pile Embed for building over water
RE: Min Pile Embed for building over water
RE: Min Pile Embed for building over water
It def seems like too much load for one pier.
Surprised you say "he doesn't know what type of soil". Seems like somebody would know something if they have driven 50 piles into it. They might not be scientific (no installation readings) but you aught to have some idea of what is commonly found on that body of water.
Lateral load transfer into the soil seems like a real challenge too.
RE: Min Pile Embed for building over water
It sounds fishy, yes. Worth looking into for sure, but it might be alright.