Long-term Monitoring of Deep Foundations

Deep foundations are used in many types of civil infrastructures, such as high-rise buildings, bridges, railway lines, and tunnels. The design and installation of these deep foundations are crucial to ensure that there is sound support and ground stability throughout the lifespan of the structures built above. In Singapore, deep foundations, such as cast in-situ bored piles, are common due to a combination of the type of soil strata and the prevalence of high-rise buildings and other urban infrastructure.

If deep foundations are poorly designed, installed or disturbed by neighbouring works, it may result in settlement, where unequal loading of the foundations causes parts of the structure to become distorted or disrupted. Where settlement is significant, structures can potentially be deemed as unsafe. Extensive and expensive remediation works may then be needed to rectify the issues. In the most severe cases, the structure has to be demolished entirely.

In current practice, a short-term static load test on a small percentage of piles is required to ensure the pile performance conforms with the approved designs. This typically involves a seven-day test on less than 10% of the overall piles installed.

However, this test only provides a snapshot of the expected performance of the deep foundations over a short duration, it does not provide real-time data for the long run. Thus, the responsibility of monitoring and maintaining the performance of a structure built on top of the foundations falls to asset owners and operators, who are required to conduct manual inspections to ensure that the structure is well-maintained and operating safely across its usable lifetime. This manual monitoring technique does not provide data from the root of the cause, providing limited information of the cause of any issues with low resolution. 

Recent studies have shown that fibre optic-based sensing can offer accurate, automated, long-term monitoring of deep foundations. Such technology has the potential to provide building owners and operators with critical performance insights of a structure in real-time and high resolution, automating the inspection process and providing information that was previously not attainable. This information would provide firm confidence that assets are operating safely within their design specifications, with data captured from day 1 of the structures installation.

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Geolutions is looking for a solution to capture and provide accurate, automated data, monitoring the performance of deep foundations over the usable lifetime of a building or structure.

The solution should:

• Eliminate the need for manual inspections of foundation piles and hence, reduce manpower;
• Enable automated data capture of deep foundation operating performance over a long period (25+ years);
• Provide reliable and accurate data with resolution down to single digit microstrain in real-time; 
• Use a wireless communication protocol that is robust enough for on-site deployment with limited signal loss or data drop;
• Provide a dashboard that allows users online access to updated data; and
• Send alerts to users if measurements exceed the normal range.

Geolutions will host the POC or pilot study at a Housing and Development Board (HDB) project involving deep foundations.

Geolutions and HDB will provide site support when testing and deploying the solution. Further, past datasets and information will be made available to the solution provider.