Abstract:
This paper describes an artificial ground freezing (AGF) application carried out to ensure both watertightness and structural support for the safe excavation of four cross passages of the Forrestfield Airport
Link (FAL) project in Perth. The line will deliver 8.5 km extension of the existing urban rail network
connecting the growing eastern suburbs of Perth with the existing suburban rail network. The proposed
soil improvement technique is adopted as a smart alternative to jet grouting from the surface since the
use of heavy equipment with long vertical mast was not allowed due to the line underpassing an airport
in operation. In this paper, we give details of the challenges and lessons learned during both design and
construction phases. Furthermore, we describe the geometry and the installation of freeze pipes in
presence of a massive steel frame, ventilation system and slurry pipes of the tunnel boring
machine (TBM) in operation. We also illustrate a web monitoring system to allow key personnel to
follow in real time the development of soil temperatures, tunnel convergences and ground surface
deformations as well as changes in the interaction between international parties involved due to the
COVID-19 pandemic.