Assessing the impact of correlated geotechnical properties on the behaviour of retaining structures

This study investigates the geotechnical intricacies of Copenhagen's Quaternary upper clay till deposits, characterized as highly over-consolidated and significantly heterogeneous, and their impact on the structural performance of secant pile walls. Through rigorous analysis, 5000 samples were generated using multivariate distribution functions. These functions were developed to probabilistically calibrate the HS-small constitutive model, taking cross correlations into account. Additionally, 5000 more samples were generated assuming independence. These samples serve as the basis for a finite element model, providing crucial data on lateral wall deflections and bending moments. The impact of cross correlations among geotechnical properties on secant pile wall response is evident. The study quantifies this impact, showing a substantial reduction in standard deviation for lateral deflections (about 20%) compared to interdependent samples. The maximum bending moment during the final excavation stage sees a more modest 50% decrease. This study not only sheds light on the importance of considering dependencies among geotechnical properties in deep excavation design but also provides a practical framework for optimizing performance and safety in similar projects.