Quality improvement by application of a revised standard – feasibility studies on 2500 soundings

Abstract

CPT is a geotechnical investigation method that, depending on the geology, has been proved to be an essential tool to establish the Geotechnical Design Model. However, doubt has been raised about the quality of the data. Hence, the feasibility to use data from CPT to evaluate reliable parameters for the Geotechnical Design Model also needs investigation. Currently, the international standard EN ISO 22476-1 [1] is being revised, and the revised version will be published in winter 2022. It will include new requirements related to quality parameters such as zero stability, zero-shift, temperature, and pore pressure response. In addition, there will be updated requirements related to the calibration of the cone penetrometer. All this is to improve the quality of the CPT data, thereby increasing the reliability of parameters evaluated from CPT. This paper presents a feasibility study. It compares the zero-shift variation depending on the type of cone penetrometer, the operator, and the geology. More than 2 500 soundings from Sweden, Norway and Finland were the basis for this comparison. The results indicate that the data quality is strongly linked to the type of cone penetrometer, its calibration, and the management of the cone penetrometer in the field.