Worldsensing launches smart tunnel lining concept

The company says the system addresses a major safety challenge in the construction of tunnels and allows engineers to make data-driven decisions from as early as the lining construction phase. It embeds sensor equipment within the concrete segments installed by the TBM, thereby avoiding costly delays of equipment installation and de-installation.

The embedded sensors allow engineering teams to get real-time data on lining stability from before the tunnel linings are installed. The data is transmitted throughout the life of the lining and can be analysed using any industry-standard visualisation software, improving engineers’ ability to make data-driven decisions relating to infrastructure safety and integrity.

The monitoring units include a Worldsensing five-channel data logger, connected securely to vibrating wire sensors such as strain gauges or pressure cells. The data loggers are housed in a polymer casing that can be embedded directly in concrete, with the casing sitting flush with the inner surface of the tunnel lining.

During construction, the data logger can send signals to a gateway installed up to 100m away in the head of the TBM, providing a real-time view of tunnel stability from the moment the lining is applied. The data logger is powered by batteries that can last up to a decade without maintenance.

This data transmission distance is limited by interference from the TBM but once the boring machine has moved on, communications can switch to tunnel-based gateways up to 3km in a straight line or 800m around curves.

Worldsensing director of global sales Matthieu Laville said the system was “a major step forward in tunnel boring safety and efficiency”.

“We can now drastically reduce the delays involved in installing and configuring tunnel monitoring systems, saving time and costs. Because the technology is completely based on wireless there is no need for costly and time-consuming cabling and splicing work once the TBM has moved on,” he said.

Worldsensing estimates the embedded monitoring solution could reduce the time and effort involved in tunnel construction by up to 25%. The concept can be applied to other types of construction, such as building or installing shafts, concrete slabs, bridge pillars, segmental bridges, diaphragm wells, precast foundations and columns and beams.