neighbouring buildings and the almost 100,000 people who
pass by the corner on any given day.
Mississauga, Ont.-based Monir Precision Monitoring was
brought in by its sister company, Isherwood Geostructural
Engineers, the shoring design engineers, and GFL
Environmental, the shoring contractor on the project, to
implement and oversee monitoring throughout the excavation
of the site and construction of the building’s foundation.
Due to the challenges posed in excavating the site – depths
of up to 28 feet in some spots and little to no easements for
shoring at others – it was quickly determined some form
of automated monitoring would be required to ensure any
settlements were quickly detected, and to safeguard workers
throughout the excavation and foundation construction.
Monir’s team chose to go with the ShapeArray system to
complement the extensive monitoring program deployed for
this site. The ShapeArray was developed by Fredericton, N.B.-
based Measurand. One of the first versions of the system was
created for motion capture technology used in live action
and animated feature films. It was subsequently adapted for
use in urban construction.
Monir general manager Samantha Ford says one of the
main reasons the ShapeArray was chosen for the project
is the flexibility the system offers. It can be deployed into
a variety of different sized casings, from inclinometer casings
to small diameter conduit pipe, and is held in place
using compression.
The system features a series of stainless-steel sensors that
each contain a micro-electro-mechanical system accelerometer
and are connected by flexible joints. The accelerometers
allow the sensors to measure tilt relative to gravity for the
purpose of recording the X, Y and Z coordinates for each segment.
Once inserted in the ground, the system is easily wired
to a data logging system that can then send detailed real-time
information about what’s happening underground via Wi-Fi
to its users. Within the data logging system is an onboard
drive that records the information in case the connection to
the sensor is lost.
“What really struck us was the ease of use, the simplicity
of the system and the applications for urban construction,”
Ford said.
“It’s delivered on a large reel. Once at site all we need is a
flat, safe work surface for us to unreel the instrument into the
casing. It’s more or less a plug and play application in terms
of the sensor itself. Where the complexity of it comes in is
knowing when and where to install the instrument to maximize
its value.”
Perhaps the biggest challenge posed by The One’s small
footprint was that workers had little ‘elbow room’ when it
came to digging or pouring the foundation because of the
existing deep foundations from other adjacent buildings
and underground utility systems. That was especially problematic
on the south and west sides of the site, where they
had very limited ability to install tieback systems. As a result,
workers had to install 13 rows of tiebacks along an extremely
narrow alleyway to transfer the load from the north to the
south sections of shoring and limit the deflection of the
corner. The design load of nearly 16,500 Kilonewtons (kN)
in this particular corner, equates to roughly 22 fully-loaded
transport trucks.
The ShapeArray provides real-time data, which was
critically important in addressing that unique challenge,
and provided an opportunity for a value-added approach,
Ford says.
“The beauty of the ShapeArray technology, which is similar
to that of inclinometer technology, is the team can be proactive
rather than reactive to changes (below grade). It provides
near real-time results of subgrade changes and there’s really
no other technology in our market at this time that can provide
that.
“The team having detailed information of the pile bending
and behaviour of the subgrade before excavating, allows for
discussion prior to movements becoming an issue that can
create delays,” she said.
GREAT CANADIAN PROJECTS
“Construction is a very
dangerous environment.
Having access to real-time
information can be critical
for protecting those workers
30 metres down in an
excavation.”
– Samantha Ford,
Monir Precision Monitoring
56 Q1 2020 www.pilingcanada.ca
/www.pilingcanada.ca
