Evaluation of SPT energy for Donut and Safety hammers using CPT measurements in Egypt

(in lingua inglese)

An evaluation of the energy efficiency of the Donut and Safety hammers commonly used in Egypt and the associated correction factor is presented herein. The energy efficiency is estimated based on a comparison between the corrected Nvalues from the SPT (Nc) and back-calculated N60 values from the CPT using well established correlations. A total of (147) SPT blow counts and corresponding CPTs at four sites in Egypt were used in analyzing the energy efficiencies of both types of hammers.