Energy Transfer in Standard Penetration Test

by Felix Y. Yokel, (M.ASCE), Leader; Geotechnical Engrg. Group, Center for BuiLding Tech., National Bureau of Standards, Washington, D.C. 20234,

Serial Information: Journal of the Geotechnical Engineering Division, 1982, Vol. 108, Issue 9, Pg. 1197-1202

Document Type: Journal Paper


An expression is derived for the fraction of the kinetic energy transferred from the hammer to the drill rod in the SPT which reflects the energy loss attributable to drill rod length. The expression is used to study the effects of rod size, and the potential effect of reducing the hammer weight and increasing the fall height correspondingly. It is shown that 95% of the energy is transferred to the drill rod when the weight of the drill rod is 75% of that of the hammer, and that the energy transfer losses in shallow borings could be reduced considerably by using a half-weight hammer, delivering half the energy used in the standard test.

Subject Headings: Energy loss | Rods | Penetration tests | Kinetics | Boring

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