The Use of Satellite Technology on Sydney Metro Northwest Tunnel Construction
The recently opened Sydney Metro North West Line includes 15km of twin running tunnels that were constructed in rock using four double shield TBMs. The selected route, with an open cut station at Cherrybrook, passes through a designated landslip zone along a steep sided ridge line. The station is in the middle of the landslip zone, with shallow tunnels either side required in order to avoid a deep cut and cover station box. During the planning stages, the risks associated with the landslip zone and boring tunnels at a relatively shallow depth were considered. There was a risk that the landslips were still active and could be accelerated by the presence of the tunnels impacting the groundwater regime. There was also considered to be a low risk that new slips could be triggered by the tunnelling works. This paper describes the geology of the landslip zone and how the landslip issues were assessed and then addressed through the use of InSAR satellite monitoring technology to review historic data to determine the status of existing slips. The monitoring was then continued during the construction period and post construction to identify any on-going movement.