Summary of the works
Client: BAM Construction
Start Date: Summer 2016
Completion Date: End 2018
- 61 Tilt sensors
- 4 Noise monitors
- 5 Vibration monitor sensors
- Wireless node and gateway system
- Calyx Online Monitoring Software™
Founded in the 13th century, Oxford is the oldest university in the English-speaking world and today is a global centre of excellence in undergraduate and post-graduate education and a world leader in research. Crucial to maintaining this position is the University’s ability to provide an excellent experience for students, as well as ensure the best possible learning and research environment. The development of the H B Allen Centre on the Acland House site at Keble College will play a vital role in this, providing accommodation for 230 graduate students and featuring a 120-seat lecture theatre, seminar rooms, an exhibition space, a café, a gym and facilities to house visiting academics.
Works began in the summer of 2016 with the demolition of the existing buildings around Acland House and Felstead House, which are being retained. Creation of a full lower ground floor under the quad at the new H B Allen Centre required excavation of the basement across the whole site and, in particular, under the listed Acland House. This saw nearly 65,000m³ of dug material being removed from the site, so a robust monitoring system was required to ensure that the retained buildings remained structurally sound during the excavation work. Collaborative consultation between ITM Monitoring, Survey Associates Ltd. and BAM’s project team resulted in a tilt monitoring solution being devised, utilising manual surveying and remote automated monitoring systems, ideally suited to ITM’s capabilities.
A total of 61 tilt sensors have been installed on the facades and inside the heritage buildings, on top of the secant pile wall, and on the walls surrounding a neighbouring pub to monitor movement caused by the excavations. These tilt sensors communicate via wireless nodes, which transmit to an onsite gateway, relaying data to ITM’s online data visualisation software – Calyx OMS (Online Monitoring Software)™ – every hour. Calyx OMS collects and displays all of the automated data from the tilt sensors – as well as the noise and vibration sensors installed at four locations and a standalone vibration monitoring unit – providing BAM with a complete picture of the structural and environmental impact of excavation and construction works on neighbouring infrastructure.
'There were a number of challenges during the instrumentation installation phase of this project, which we worked closely with the client and other partners to overcome. Firstly, when installing tilt sensors directly into the secant pile wall, there was a high chance of them being damaged, so we devised a protective enclosure to prevent this from happening, ensuring that the sensors continue to function as required. Secondly, due to Acland House being a listed building, there were a unique set of challenges associated with working on a historical building. Heritage England were involved as consultants to ensure that any works carried out were mindful of the preservation of the retained buildings. We devised low impact installation methods, and explored wireless monitoring techniques which reduced the use of intrusive equipment and extensive cable runs, ensuring that everything we did onsite had as little impact to the listed building as possible. This is an incredibly exciting project to be involved in and we look forward to seeing how the monitoring system informs the ongoing construction works.' Tom Scott, ITM Project Manager for the Keble College contract
ITM’s solution allows us to remotely monitor the site and fulfil the client’s requirements of recording and alerting to movement. Data visualisation through Calyx is easy to navigate with information clearly shown using drawings and photos from site. ITM have performed well and we would definitely work with them in the future. Site Manager for BAM Construction, Ashley Price