Monitoring, Back analysis and Redesign of a Deep excavation Retaining system in marl formation. Case history, Modelling and Interpretation

We present in this paper a case study of retaining system of a deep excavation in a marly material in Beirut. The objective of this study is to redesign the retaining system using a new set of mechanical parameters considered more realistic than those derived from the initial site investigation. The methodology incorporates back analysis of displacements measured on-site, with horizontal deflections assessed using three vertical inclinometers. The experimental results were simulated through numerical calculations utilizing finite element code. Our results reveal that the new mechanical parameters lead to more optimal designs, enhancing the stability and performance of the retaining structures under consideration. This paper emphasizes the importance of accurate parameter selection in geotechnical practices, particularly within complex geological contexts like that of Lebanon, and highlights the need for effective monitoring and validation methods for excavation retaining systems. The findings contribute to improved understanding and management of deep excavation processes in similar marl formations, aiming to mitigate the risks associated with inadequate or excessive structural designs.