Monitoring sprayed concrete lining with BeMo

BeMo and the University of Birmingham have conducted a laboratory experiment at NBIF to evaluate the use of optical fibres to replace automated Total Stations and optical targets to monitor the performance of sprayed concrete lining during construction.

An engineer calibrates an optical fibre pipe

Both the traditional displacement measurement and optical fibre strain data were used in a utilisation index to estimate the residual capacity of the sprayed concrete lining and compared. The results demonstrated that optical fibres provide a much richer data environment than discrete point targets and could replace these in the future. This has the potential to provide not only enhanced data during tunnel construction, but also during the operational lifetime of the tunnel thereby having a significant impact on improvements to proactive maintenance thereby ensuring improved health and safety and economic benefits.

The collaboration is introduced in the video below:

Using optical fibres to monitor sprayed concrete lining with BeMo

BeMo and the University of Birmingham have conducted a laboratory experiment at NBIF to evaluate the use of optical fibres to monitor the performance of sprayed concrete lining during construction

Transcript

Thomas Wechner

BeMo is specialised in constructing tunnel and heavy civil engineering, caverns and galleries. BeMo has chosen the National Buried Infrastructure Facility because of the brilliant reputation of the University of Birmingham and the good connection to the tunnel team at Birmingham University. Normally, in tunnelling, we monitor deformations with targets and a laser, which is a good process but has also some dis-benefits like the targets can be destroyed.

Dr Alfred Stärk

A tunnel is not a clean environment, so there's dust. There's noise. There's heat. The temperature could affect the readings.

Thomas Wechner

Our vision is that we use fibre optics in the future instead of the targets. The benefit would be that they are embedded in the shotcrete, so they cannot be destroyed. Dr

Alfred Stärk

A clear benefit of using optical fibres during construction is a lot higher accuracy. The benefit for the clients are massive as well because the fibre optics can stay in the lining, so giving readings over probably the lifetime of the tunnels. And we're talking about 100 years or even 150 years, so it gives us certainty for the client how the long-term behaviour of the lining is. The impact for BeMo if the research will be successful should be increased the level of safety, stability assessment. In the end, it's much more sustainable.

Thomas Wechner

We believe implementing this system in the future will help us to build the tunnel more safely, yeah, and also more efficient, and at the end, we're going to get more value for money.