CPTU-based settlement modelling for Kujala test embankments on overconsolidated silty clay: A probabilistic approach

Abstract

Sounding resistance, such as CPTU cone tip resistance, is often used to estimate the settlement of the subsoil when designing ground-supported structures. This paper utilizes CPTU-based probabilistic modelling to estimate the settlement of two test embankments located in Finland. The model is based on an empirical correlation between CPTU net cone resistance and constrained modulus (M0 ), described by factor α. Besides the existing correlation (prior distribution of α), this paper also considers the site-specific observations via Bayes' theorem. By means of Monte Carlo simulation, the settlement histograms were produced and the results compared to the observed settlements. Lastly, the effect of dry crust on the embankment load transmission was considered in order to decrease the model bias. The results indicate that for the other embankment the effect of dry crust has to be considered in order to acquire satisfactory results. It is concluded that this CPTU-based settlement model might be suitable for stiff, overconsolidated silty clay soils in Finland. However, model calibration using site-specific oedometer test data is recommended. On the other hand, such simplified model with a singular modulus should not be used for normally consolidated clay subsoils.