Drilled Pier L/d ratio
Drilled Pier L/d ratio
(OP)
In drilled pier design for compression loading, and in fairly uniform alluvial soils, I typically follow the FHWA recommendations for limiting the length:diameter ratio to be less than 30, adopting the rationale that load transfer below this depth attenuates.
Beyond the 1999 FHWA Drilled Shafts Manual statement that "A good rule of thumb is that the ratio of length (L) to diameter (B) of a drilled shaft should be 30 or less", does anyone have any references or experience in adopting OR exceeding this design length limitation?
Thanks
Beyond the 1999 FHWA Drilled Shafts Manual statement that "A good rule of thumb is that the ratio of length (L) to diameter (B) of a drilled shaft should be 30 or less", does anyone have any references or experience in adopting OR exceeding this design length limitation?
Thanks





RE: Drilled Pier L/d ratio
RE: Drilled Pier L/d ratio
sorry no references.
RE: Drilled Pier L/d ratio
RE: Drilled Pier L/d ratio
I am aware of the IBC Ch 18 note which states something to the effect that piers with an l/d ratio > 30 can be installed under the supervision of a geotechnical professional. I take this to be addressing constructability from the standpoint that the installation of deep slender piers (perhaps exceeding l/d = 30 to reach end-bearing) needs special QAQC attention. Or do you think it is simply intended to allow design of friction piers with l/d > 30?
RE: Drilled Pier L/d ratio
i'd try to find references for your particular part of the country and/or geology if possible.