ABSTRACT
Soil nail walls are increasingly adopted as Support of Excavation (SOE) systems in urban deep excavations. They act as cost-effective, versatile, and safe temporary or permanent shoring structures. In this study, a hybrid soil nail wall system is evaluated, combining conventional nailing with improved monitoring integration to enhance wall performance. Monitoring data obtained using Laser Total Station recordings provided insight into wall deformation during and after construction. Finite Element (FE) modelling with Plaxis 2D was applied to analyze staged construction and post-construction deformation behaviour. The results demonstrate that post-construction deformations can be significantly higher than immediate deformations, emphasizing the need for hybrid approaches. The FE analysis and Load Relaxation Factor (LRF) calibration provided reliable predictions that align well with field monitoring, highlighting the contribution of hybrid soil nailing systems for safer urban excavations. The measurements were collected daily during excavation and weekly after wall completion, with reflectors placed along the top nail rows and at critical wall sections near adjacent structures.
To ensure optimal performance of the system, it is essential to monitor the behaviour of soil nail walls through the excavation and after construction. By analysing monitoring data, valuable insights can be gained into the performance of the walls during and after construction that can be used for back analysis and design modifications, and leading to improvements in SOE systems design.
In this study, various numerical models have been developed using different modelling approaches. The case studies demonstrate that post-construction deformation rates can vary between walls, depending on factors such as soil nail system design and geotechnical conditions at the excavation site. A thorough understanding of these variables is crucial for optimizing the performance of SOE systems in deep urban excavations.
