Monitoring during construction stage

Inclination sensor

Water table level sensor

Checking how and to what extent excavation work would affect a temporary retaining wall structure has always been imperative to the construction work’s safety. However, with conventional methodologies in the construction industry, this can only be done infrequently. This project was a pilot project to verify the benefits that continuous real-time IoT monitoring could bring to the construction industry.

3D model of the monitoring site

Our sensors were deployed to a construction site at Fung Shing Street, Wong Tai Sin, Kowloon. The excavation lateral support works consisted of a temporary retaining wall built with a row of concrete-filled pipe piles and welded on steel plates to seal up the inter-pipe pile spaces. Excavation work was carried out on one side of this temporary wall, while our sensors measured the inclination of the retaining wall and the underground water table level on the opposite side of the wall.

The contractor at the site had their mobile devices installed with an app for monitoring sensors’ reported readings, and should measured tilt angle or underground water table level exceed preset safety thresholds, warning signals will be immediately issued to the mobile devices to call for immediate attention and to arrange remedial works if necessary. Monitoring was conducted from January to March 2017.

Sensor measurements showed that the sensors could detect minute movements which were otherwise unnoticeable. Minute changes in the retaining wall’s tilt angle could be detected when there were construction activities at the site, i.e. during working hours. In this way, overtime work could also be detected. Overall, monitoring results showed that construction activities throughout the monitoring period were carried out without affecting the stability of the retaining wall and the underground water table level outside the wall. Sensor measurements were verified with traditional surveying results and both were found to agree with each other.

This demonstrates that with Pyxis, users can have access to accurate real-time measurements of factors concerning the site’s safety at their fingertips 24/7 without incurring human resources, etc. The additional resources available in this way can then be channelled to other works and improve overall productivity at the job site.

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