Page 177 - Civil Engineering Formulas

114 CHAPTER FOUR

degree. For piles less than 50 ft (15.2 m) long, K is more likely to be in the
range of 1.0 to 2.0, but can be greater than 3.0 for tapered piles.
Empirical procedures have also been used to evaluate f s from in situ tests,
such as cone penetration, standard penetration, and relative density tests. Equa-
tion (4.17), based on standard penetration tests, as proposed by Meyerhof, is
generally conservative and has the advantage of simplicity:

N
f s (4.24)
50
where N average standard penetration resistance within the embedded length
2
of pile and is given in tons/ft .*
f s

*Meyerhof, G. G., “Bearing Capacity and Settlement of Pile Foundations,” ASCE Journal of
Geotechnical Engineering Division, 102(GT3):1976.