PILEINSPECT · Integrity Testing of Deep Foundation Piles

A hundred thousand kilometres of piles are installed yearly in Europe. Problems can occur during pile driving including spalling of concrete at the pile’s head or point and transverse or spiral cracking. Industry figures suggest that as many as 3-5% of piles fail during installation. If a failure is detected, the cost of that pile is increased 4 times due to the remedial work needed to replace it. If a failure is not detected during installation of the new pile, the results can be more catastrophic with costs sometimes exceeding €1 M for a single failure.Current pile inspection techniques involve dynamic load or sonic integrity testing. These are relatively fast to perform. However, the quality of results depends strongly on the knowledge and skill of the operator. It has been found that small defects that are less than about 0.4m (quarter wavelength) are difficult to detect. Some studies also indicate that defects representing less than 50% of cross sectional area are not detectable via sonic integrity testing.PileInspect aims to develop ‘best practice’ for inspecting the integrity of cast-in-place and pre-cast concrete piles and of steel piles. We propose to replace the instrumented hammer and pile driving hammer with a portable shaker which will ensure repeatable, tailored excitation spectra, and should dramatically improve accuracy of estimation of the proposed diagnostic features.Highly innovative signal processing methodologies (based on time frequency analysis techniques formulated for non-stationary signals) could be employed in order to try to increase the quality of diagnosis and perform automatic defect recognition.