Peter Reading, director, Julian Lovell, managing director, Keith Spires, operations director, Equipe Training, and John Powell, technical director, Geolabs. This paper was first published in GE’s May 2010 issue.
In July 2007 the European Standard covering the Standard Penetration Test (SPT), BS EN ISO 22476-3: 2005, was fully implemented into UK practice. It is similar in general terms to the old BS1377 Part 9: 1990, but requires that the energy ratio (Er value) be measured for the hammer when the measured penetration resistance (N value) is going to be used for the quantitative evaluation of foundations or for comparing results.
The standard requires that a certificate of calibration of the Er value be available and provides a recommended method for determining the energy ratio and reporting the results. This paper focuses on the measurement of the energy ratio, and the results and additional criteria that can be used to determine best practice and quality assurance for the SPT test.