Statistical analysis of CPT tip resistances
Selecting proper values for soil parameters is a crucial aspect in geotechnical engineering. Geomaterials exhibit an inherent, natural variability, which can be assessed by statistical methods. CPT data lend themselves well for statistical analysis, given the large amount of data retrieved in a single test. The aim of this study was to examine the guidelines for statistical parameter estimation set out in Eurocode 7, as applied to CPT tip resistances. First, the guidelines and methods for estimation of fractiles and mean value with a given confidence level were reviewed. Second, a number of 125 CPT datasets were analyzed: the goodness-of-fit tests have shown that the common assumption of a normal distribution does not hold. Third, different estimation methods for the 5% fractile, the mean and the median were evaluated with regard to robustness and efficiency.