Accuracy classes for cone penetration tests (CPT) have been in use since 1996. From 2012, industry use of CPT accuracy classes rapidly increased, when this type of classification system was included in the international standard ISO 22476-1:2012 on the electric cone and piezocone penetration test. The ISO standard adopted the term “application classes”, bringing together accuracy classes and applications for use of CPT results. Differences in interpretation about compliance with the ISO box values for accuracy became gradually apparent. Unfortunately, the interpretational challenges emerged from contractual disputes, unnecessary re-work and CPT results assigned higher confidence than actual. This paper reviews multiple interpretations and adaptations on compliance with the CPT accuracy/ application classes of ISO 22476-1:2012. Implications for practice are addressed and suggestions are given for future direction.
Proceedings of the XVII European Conference on Soil Mechanics and Geotechnical Engineering - ECSMGE 2019: Geotechnical Engineering Foundation of the Future