Statistical soil characterization of Italian sites for reliability analysis

The paper is a review of the most commonly used techniques and methods for the estimation of inherent variability and uncertainties concerning soil physical and mechanical properties estimation. The methods illustrated in the following as, among others, intraclass correlation coefficient method, the Vivatrat procedure, the Cusum method and the Bartlett modified method are described theoretically and applied to three types of Italian soils in order to give useful suggestions for common geotechnical design activity. Furthermore reliability approach is also presented and some classical methods are dealt with here as FORM (first order reliability method) and SORM (second order reliability method). Finally an example of the reliability analysis application to a pile design is presented and discussed. Accordingly the evaluation of the reliability index of the global safety factor is carried out in order to show that the variation the safety factor can suffer on its level of reliability by taking into account the variability structure of physical and mechanical soil properties.