Foundation barrettes during load testing: strain and crack analysis

The aim of the project was to verify the performance of foundation barrettes and the jet grouting injection underneath them. To this end, high-quality monolithic sensors (6 EpsilonSensors and 13 EpsilonRebars) were installed and used to measure strain distributions during the mechanical loading tests. The design of the system made it possible to look deep into the underground parts of the structural system, which was inaccessible to conventional measurement techniques.

DFOS Sensors Installed: EpsilonSensor and EpsilonRebar

Project challenges

How to apply non-invasive diagnostics in demanding historic structures?
How to get precise measurement data to detect local damage and imperfection?
How to measure detailed strain profiles over the entire height of the brick masonry wall?

Benefits of using the DFOS monitoring system

Control of the barrette performance in reference to theoretical predictions
Analysis of the interraction between the barrette and surrounding ground
Detection and estimation of size of thermal-shrinkage cracks along the depth
Strain measurements within the jet grouting injection below the barrette

Results of using the DFOS monitoring system

The graph shows example strain profiles registered by EpsilonSensor along the barrette depth during subsequent load steps. Local peaks on the negative side correspond to thermal shrinkage cracks closing under compression. Information from thousands of measurement points from multiple sensors was used for detailed structural analysis.

Technical specifications

17 750 measurement points
355 m of sensing path
6 x ES + 13 x ER
short-term (load tests)

Example results

Recomendations (optional)

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John Doe

Project partner

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