London Underground tunnel monitoring for a new hotel development in South London.
The project
The proposed development includes the construction of a new hotel building along with a single-storey basement.
The basement substructure will be directly adjacent to London Underground tunnels running under the nearby street.
The challenge
The hotel basement and foundation construction meant that the London Underground tunnels and Thames Water assets running adjacent to the site could be susceptible to movement caused by the piling, excavation and construction works.
GEO-Instruments were responsible for monitoring the 3D movement of three Northern Line Tunnels in the zone of influence.
The solution
GEO-Instruments provided a comprehensive monitoring package including line and level, track geometry and condition surveys.
More than 100 3D retro survey targets were installed in the LU tunnels. These were surveyed on a weekly basis during LU engineering hours.
Alongside the manual monitoring, 10 wireless biaxial tiltmeters were installed to the tunnel crown to provide 24-hour, real-time monitoring of tunnel movement.
Line and Level surveys were required to accurately determine the position of the London Underground tunnels before the commencement of piling works.
Monitoring survey data was collected and presented with GEO-Instruments’ QuickView online platform.
Alert triggers were set at limits defined by the specification and automated alerts were configured so the site team could receive alarm notifications if thresholds were breached.