INSTRUMENTED STATIC LOAD TESTS ON FOUNDATION PILES

Static Load Tests (SLTs) on pile foundations are a crucial tool for understanding and optimizing the design of pile foundations. Test piles are often instrumented with strain gauges. The use of optical fibres for this purpose offers significant advantages over traditional strain measurement methods (such as extensometers based on electrical resistance or vibrating wire) in terms of ease of installation, as well as the quantity and quality of data collected.

The optical fibre is made of a fibreglass. Elongation or shortening of the fibre will cause a change in the light transmission in the optical fibre. The acquisition system is able to measure those changes.

At Buildwise, two different technologies are often used; FBG and BOFDA. The FBG type is a discontinuous measurement while the BOFDA type is a continuous one.

Buildwise database of approximately 300 results of SLTs provides the framework for tests conducted as part of the certification of pile systems. The measured load-bearing capacities are compared with the calculated capacities (in Belgium, based on CPTs). The comparison is made not only on the total bearing capacity but also on the shaft and base bearing capacities.

An automatization of the pile calculation, in accordance with the Belgian standard has also been developed. The presentation will elaborate on these various aspects, including the instrumentation of piles with optical fibres, the execution of load tests, the development of a robust database, and the standardization of calculation methods for pile system certification.