Adopting Numerical Models for Prediction of Ground Movements Induced by Deep Excavation

Abstract

Control of ground surface settlement induced by deep excavation is of major concern in order to attain safety of adjacent structures and utilities against excessive or differential settlements. Accurate prediction of ground surface movements is an important design criterion in the analysis and design of excavation supporting systems. Many codes of practice are based on a design criterion that satisfies a factor of safety preventing collapse of the system and its surrounding soil. In this research, finite element modeling is adopted to numerically simulate the performance of deep excavation systems and the associated ground movements. The soil behavior was simulated using two types of models; the Mohr-Coulomb model (MC) and the Hardening Soil Model (HS). Field data from monitoring a real deep excavation case history of a retaining system was considered to check the validity of the proposed numerical modeling. A simpler equivalent section replacing the multi-layered soil profile was verified. Then, a sensitivity study has been conducted to study the influence of major parameters that affect ground movements induced by deep excavation. The results of the parametric study were accomplished to construct design charts and drive empirical equations by implementing a design parameter, called the "Stiffness Ratio (R)”, that represents the supporting system stiffness. From these suggested charts and equations, the percentage of maximum vertical ground movements to wall height can be estimated.