During the construction of structures like high rise buildings, underground garages, underground mass transport systems, and underground water sewer systems, deep excavation is required at several levels. Excavation in soft ground induces ground movement which imposes a threat to nearby sensitive structures in the zone of influence. Hence, deep excavation risk assessment and foundation crack monitoring are crucial at all the levels.
Deformation must be limited to permissible levels in a deep excavation. Suitable instrumentation is needed to monitor the deformations at various levels for safety during and after the deep excavation.
Instrumentation is needed in deep excavation sites to ensure the safety of excavation and influence zone, to check whether design considerations are being followed, to record long term behaviour and to have legal judgements by maintaining factual data and information.
Instrumentation is done to monitor the underground pore water pressure, retaining side walls, surrounding soil and structures in the influence zone. The most commonly employed monitoring attributes in the excavation process includes the structures or the soil movement, the structures and soil’s stress/strain, and the water level including water pressure.
Encardio-Rite’s wide range of geotechnical instruments is used to monitor deep excavations. The instruments used include:
An inclinometer to measure lateral deformation of soil
Multipoint borehole extensometer to measure the settlement of ground surface
Vibrating wire piezometer to measure the upliftment of central post and the heave of excavation
Strain gauge to measure strut load
Anchor load cells to monitor stress of the retaining structures
Inclinometer to monitor retaining wall inclination
Vibrating wire piezometer to measure water pressure within and outside the excavation zone
Tiltmeters to measure building tilts
Surface settlement monitors to do surface monitoring
Geodetic surveys by Prism targets are done to monitor the 3-D movement of the structures.
Encardio Rite provides online data monitoring for all the instruments provided and installed at the site. The heart of the online structural monitoring instrumentation systems is the Web Data Monitoring Service offered by Encardio-Rite to users anywhere in the World. It is a web-based data management and presentation tool for data collected by model ESDL-30 range of data logger. Multiple authorized users at different locations are allowed to view any data or report from the same site simultaneously. Each user is assigned an individual password for access to the logged data. Graphs & reports can be viewed using popular web browsers like Microsoft internet explorer or Mozilla Firefox amongst others. The server for the above WDMS services is located at Encardio-rite premises and is maintained 24 x 7.
