Multivariate approach in reliability-based design of a sheet pile wall

In light of a restricted budget, there is a need to stress on the potential savings in conducting qualitative geotechnical investigations. This paper presents a case study on how site investigation efforts can be linked to potential savings in designing a sheet pile wall in central Sweden. The uncertainty in the undrained shear strength is a measure of investigation effort and have been evaluated from multivariate information, several investigation methods. A multivariate analysis (MVA) procedure based on Bayesian statistics was used to cross-validate information obtained by different investigation methods, thus allowing the uncertainty or effort to be updated (reduced) when additional investigations are included in the analysis. The uncertainty was evaluated for two sets of investigations, one of which included additional measurements and hence less uncertainty. A reliability-based design method, FOSM, was then used to study how the additional investigations affected the evaluated uncertainty and one design constraint of the sheet pile wall, namely the depth of penetration. The results show that the depth of penetration can potentially be reduced by approximately 11% of the total wall area.