peterb1441
Geotechnical
Are there any correlations between the Standard Penetration Test N value and pile driving records, or various pile driving hammers?
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SPT N values and pile driving records
- Thread starter peterb1441
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peterb1441,
Various state DOTs that I have worked with have had this data implicit in their design capacity formulae. These agencies are really the only ones who can invest in large-scale comparisons of pile driving data with data collected during investigations.
See Iowa DOT and Illinois DOT design guidance for driven piles in the respective Bridge Design Manuals. Note that FHWA mandates may have induced some of the more "state-specific" design guidance to conform more with AASHTO and FHWA design methodolgies in recent years, so older design manuals may present more explicit relationships developed from projects across the jurisdiction. The DOT's will generally retain copies of old design manuals so they can recall to what standards older structures were designed.
Jeff
Various state DOTs that I have worked with have had this data implicit in their design capacity formulae. These agencies are really the only ones who can invest in large-scale comparisons of pile driving data with data collected during investigations.
See Iowa DOT and Illinois DOT design guidance for driven piles in the respective Bridge Design Manuals. Note that FHWA mandates may have induced some of the more "state-specific" design guidance to conform more with AASHTO and FHWA design methodolgies in recent years, so older design manuals may present more explicit relationships developed from projects across the jurisdiction. The DOT's will generally retain copies of old design manuals so they can recall to what standards older structures were designed.
Jeff
Are you trying to use SPT values to predict pile capacities? If so, Meyerhof presented a method to do this.
The ultimate end bearing (in tons) is estimated by
Qp=0.4 (N/B) Df Ap <= 4 N Ap for sand
and
Qp=0.4 (N/B) Df Ap <= 3 N Ap for nonplastic silt
where N is the SPT value corrected for hammer energy and overburden,
B is the pile width,
Df is the length of pile in the stratum,
Ap is the area of the pile point.
The ultimate unit skin friction in tons per square foot is estimated by
fs=N/50 <= 1 tsf
The ultimate end bearing (in tons) is estimated by
Qp=0.4 (N/B) Df Ap <= 4 N Ap for sand
and
Qp=0.4 (N/B) Df Ap <= 3 N Ap for nonplastic silt
where N is the SPT value corrected for hammer energy and overburden,
B is the pile width,
Df is the length of pile in the stratum,
Ap is the area of the pile point.
The ultimate unit skin friction in tons per square foot is estimated by
fs=N/50 <= 1 tsf
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