Cornell Tests Smart, Resilient Underground Infrastructure

The future looks “smart” for underground infrastructure after a first-of-its-kind experiment conducted at Cornell.

Like many of today’s household devices, modern infrastructure is gaining the ability to collect and exchange valuable data. Wireless devices can monitor the health of buildings and bridges, for example, in real time.

But wireless systems for underground infrastructure, such as utility pipelines, are much more difficult to test in the field, especially during rare and extreme events such as earthquakes.

The Cornell facility set out to change that by testing several advanced sensors developed by researchers at the University of California, Berkeley, and the University of Cambridge Centre for Smart Infrastructure and Construction. The sensors – which can collectively measure strain, temperature, movement and leakage – were installed along a 40-foot section of a hazard-resilient pipeline being tested for earthquake fault-rupture performance.

The pipeline itself is innovative, produced by the company IPEX using a molecularly-oriented polyvinylchloride material engineered to stretch, bend and compress as it withstands extreme ground deformation similar to that occurring during earthquakes, floods and construction-related activity.

Engineers from Oakland, California, and Vancouver, British Columbia, traveled to Ithaca to watch as the pipe experienced a simulated fault rupture while buried inside a hydraulically powered “split basin” filled with 80 tons of soil.

The test was the first use of the advanced sensors for the purpose of monitoring buried infrastructure, and gave an unprecedented look at the pipe’s ability to elongate and bend while being subject to ground failure.

“It was a fantastic performance. It did really well,” said Brad Wham, a geotechnical engineering postdoc at Cornell. “It was able to accommodate 50 percent more ground deformation than the last design based on modifications Cornell suggested from our testing four years ago.”

In addition to the scores of instruments installed for the large-scale test, new technologies employed included:

Distributed strain sensing – A laser pulse is injected through an optical fiber cable glued to a pipe. By examining the interaction signal that is generated at every point of the fiber, it is possible to obtain strain values continuously along the pipeline.

Fiber Bragg grating sensing – A special fiber-optic line that splits and diffracts light into wavelengths, allowing it to monitor bending and axial deformations accurately at discrete points, especially at pipe joints.

Frequency-domain reflectometry, wireless sensor network – Metal prongs that use an electric field to measure changes in soil moisture and detect leaks. The device is battery powered and can wirelessly transmit data through soil using a coupled magnetic induction and electromagnetic wireless sensor network system.

Smart joint-opening detection – Small magnets are attached at pipe joint locations. Once a pipe has stretched or compressed to a specific limit, the magnets conjoin to trigger the wireless sensor network to initiate the monitoring.

The sensors drew interest from the attending municipal engineers, who need new ways to monitor the performance of underground infrastructure. And as cities begin to adopt the sensor technologies, more data will exist not just for infrastructure, but for the surrounding environment as well.

“You can learn something about sources of subsidence, corrosion that affect other structures, or something about the geographic distribution of earthquake or hurricane damage, which then allows you to make improved decisions about emergency response,” said Tom O’Rourke, professor of civil and environmental engineering and principal investigator of the research project.

The test also proved that sensors provide valuable feedback to companies like IPEX that want to advance the engineering behind new products and improve systemwide performance.

Read more: Cornell

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Taxonomy

• Infrastructure
• Urban Water Infrastructure
• Infrastructure Management