Non-destructive methods, thank to their low cost, offer the opportunity to test a large amount of piles, detecting those that may be affected by anomalies.

The more expensive load tests can subsequently be limited to a more limited number, with consequent economic advantage.

Among non-destructive methods, here below the most widespread are listed:

Ultrasonic cross hole method: method used to measure seismic velocities based on traveltime measurements of a pulse propagating through the pile. The pulse is represented by ultrasounds recorded by a transducer (receiving probe). Probes are first lowered to the bottom of the inspection borehole and, while recovered up to the surface, measurements are recorded every 10 cm.

Sonic Integrity Test: the head of the pile is hit by a hammer in order to produce a compressional wave propagating along the pile. The pile base, as well as all possible discontinuities affecting it, reflects this wave. The movement of the pile head, caused by reflected waves, are recorded by an accelerometer and converted to velocity.

Pile integrity test: this method is based on the mechanical impedance measurement of a pile subject to harmonic vibrations; it allows us to analyze the ground-structure interaction.

It also allows us to determine the pile geometrical characteristics (length, column section area), verify the presence of discontinuities, estimate point element, estimate the elastic break down of the pile.