Pile driving formulas

Intuitively, it ean be expeeted that piles diffieult to drive have more load earrying eapaeity that those that are easier to drive. Many empirieal eorrelations have been therefore developed to relate the hammer weight, blow eount and other faetors with the statie load eapaeity of driven piles. These relationships are eolleetively known as pile driving formulas. 

The basie relationship eommon to all pile driving formulas is 

L of cut-off level R.L of toe of driven ] Length of pile from c Measured temporary compression  

Penet- ration (ft) Height of hammer drop (ft) No. of Blows Remarks Penetra- tion (ft) Height of hammer drop (ft) No. of blows Remarks 

A more recent form of the Engineering News Formula called the Modified Engineering New Formula is written as follows  

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There are also several other pile driving formulas such as the Canadian National Building Code formula, the Danish formula, the Gates formula, the Janbu formula, the AASHTO formula, the Navy-McKay formula, and the Pacific Coast Uniform Building Code formula. 

At sites where a full-scale load test is not available (such as for small projects), pile driving formulas may be used to access the static load carrying capacity of driven piles. Each pile has a required load capacity that corresponds to a certain minimum acceptable blow count. Therefore the pile is driven until it reaches the specific blow count (refusal). In large projects where static load test is usually carried out, tiie pile driving formulas may be modified to match the load test results. This custom formula is then applied to other piles at the site, and thus provides a mean of extrapolating the load test results, and for purposes of construction control. 

ASCE 1941. Pile driving formulas. Proceedings ASCE. 67(5) 853-866. 

Methods to estimate axial pile load capacity based on pile driving formulae have been described in Chapter 5. In this section, we describe the dynamic methods that are based on the wave equation analyses. 

Pile driving formulas are generally considered as unreliable. The alternative is to use the dynamics of pile driving in more detail, and this method is called the wave equation method. This method provides a more accurate function of capacity versus blow count helps optimize the driving equipment, and computes driving stresses. 

Haswell, C.H. (1898). Reminiscences of early marine steam engine construction and steam navigation in the USA from 1807 to 1850. Trans. Inst. Naval Architects 40 104-113. Haswell, C.H. (1899). Pile-driving formulas Their construction and factors of safety. Trans. ASCEA2-. 261-I M. 

Driven pile Side and end All Sanders pile driving formula (1850 Poulos and Davis, 1980)... 

Sorensen, T. and B. Hansen. 1957. Pile Driving Formulae - An Investigation Based on Dimensional Considerations and a Statistical Analysis, Proc. 4th International Conference On Soil Mechanics, London, Vol. 2, pp. 61-65. 

Driven Pile Foundation, Pile Driving Systems and Formulas... 

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